South American Region Research Articles

Use of multiple South American nonbreeding regions and seasonally distinct migration routes by an individual Scarlet Tanager (Piranga olivacea)

Use of multiple South American nonbreeding regions and seasonally distinct migration routes by an individual Scarlet Tanager (Piranga olivacea)

Digital health divide and digital technologies for treating substance-related disorders in Argentina

Abstract Argentina is a country located in the South American region with more than 45 million inhabitants. According to the National Institute of Statistics and Censuses, over 92% of the population lives in urban areas. Additionally, 47% households do not have access to computers, and 12% lack availability of the internet. The present case study demonstrates the effects of the digital divide regarding the use and access to digital technologies in patients who underwent virtual treatment for substance-related disorders in a mental health service in the city of Córdoba, Argentina. This treatment modality included virtual consultation with a psychologist and WhatsApp groups for mutual support. The data obtained is part of a larger research project aimed at evaluating access to digital healthcare treatment, quality of life and patient satisfaction with the use of digital tools for treating substance-related disorders. Participants were adults between 25 and 60 years. The majority of the patients who were surveyed presented cognitive impairment and unemployment status. Those who completed secondary school (79%), stated that virtual consultation was easy to conduct (83%) and WhatsApp group texting information for mutual support was very difficult to comprehend for participating actively (63%). On the other hand, participants who only reached primary school (21%) declared that virtual consultation was easy to do (71%) and WhatsApp group texting information for mutual support was very difficult to comprehend for participating actively (87%). Concerning access, 78% of participants answered that they have difficulties with the availability of digital devices (i.e., smartphones, computers, or tablets), internet connectivity and privacy at home or work for undergoing digital treatment.

Recent increase in Candida auris frequency in the SENTRY surveillance program: antifungal activity and genotypic characterization.

We observed an increase in the frequency of Candida auris among invasive candidiasis isolates in the 2022 SENTRY Antifungal Surveillance Program compared to prior years: ≤0.1% before 2018, 0.4%-0.6% from 2018 to 2021, and 1.6% in 2022. C. auris isolates were collected in seven countries, but 28 (35.9%) isolates were recovered in the USA (five states; more common in New York, Texas, and New Jersey) and 26 (33.3%) in Panama. Greece and Turkey had 12 and 9 isolates, respectively. Overall, 82.1% of the isolates were resistant to fluconazole; 17.9% were resistant to amphotericin B; and 1.3% were resistant to caspofungin, anidulafungin, or micafungin (Centers for Disease Control and Prevention tentative resistance breakpoints). Rezafungin inhibited 96.2% of the isolates (Clinical and Laboratory Standards Institute susceptibility breakpoint). Pandrug resistance was not observed, but 17.9% of the isolates were resistant to fluconazole and amphotericin B. South Asian (Clade I) isolates were most common (n = 40, 51.3%); of these, 97.5% were resistant to fluconazole and 30.0% were resistant to amphotericin B. Thirty (38.5%) isolates belonged to the South American region (Clade IV), and 56.7% of those were resistant to fluconazole and 6.7% to amphotericin B. Seven isolates belonged to the South African Clade III and one to East Asian Clade II. Erg11 (Y132F, K143R, and F126L) and MRR1 (N647T) alterations were detected. One isolate that was resistant to all echinocandins carried an FKS R1354G alteration. Two isolates displayed elevated rezafungin minimum inhibitory concentration (MIC) values but low MIC values against other echinocandins and no FKS alterations. As C. auris is spreading globally, monitoring this species is prudent.

Projected changes in heatwaves over Central and South America using high-resolution regional climate simulations

Heatwaves (HWs) pose a severe threat to human and ecological systems. Here we assess the projected changes in heatwaves over Latin America using bias corrected high-resolution regional climate simulations under two Representative Concentration Pathway scenarios (RCPs). Heatwaves are projected to be more frequent, long-lasting, and intense in the mid-century under both RCP2.6 and RCP8.5 scenarios, with severe increases under the RCP8.5 scenario. Even under the low emissions scenario of RCP2.6, the frequency of heatwaves doubles over most of the region. A three- to tenfold rise in population exposure to heatwave days is projected over Central and South America, with climate change playing a dominant role in driving these changes. Results show that following the low emission pathway would reduce 57% and 50% of heatwave exposure for Central and South American regions respectively, highlighting the need to control anthropogenic emissions and implement sustainable practices.

Assessing the Effects of Chinese Foreign Direct Investment on Green GDP Development in North and South American Regions

This study aims to investigate the impact of foreign direct investment (FDI) on the growth of green GDP (GGDP) in North America and South America. The research is based on a comprehensive dataset covering the period from 2009 to 2019, drawn from multiple countries. By employing a two-way fixed-effects model, the study analyzes the effects of key factors, including FDI, trade openness, economic development level, urbanization level, population size, and industrial structure on GGDP growth.The findings indicate that, in North America, both FDI and the level of economic development exert a significant positive influence on GGDP growth, whereas trade openness demonstrates a negative impact, suggesting that increased trade activities may exacerbate environmental pressures. In South America, while the level of economic development shows a significant positive correlation with GGDP, the effect of FDI is not statistically significant. The study recommends that policymakers focus on enhancing the effectiveness of foreign investment and implement stricter environmental protection policies to ensure that trade activities do not adversely affect the environment. Furthermore, there is an urgent need to adjust the current industrial structure to promote a transition toward more sustainable development models. Ultimately, this research emphasizes the importance of ensuring environmental sustainability while fostering foreign investment and economic growth to achieve long-term growth in green GDP.

South America is becoming warmer, drier, and more flammable

South America is experiencing severe impacts from climate change. Although the warming of the subcontinent closely follows the global path, the rise of temperatures has been more pronounced in some regions, which have also seen a parallel increment in the occurrence of droughts and weather conditions associated with enhanced fire risk. Here, we use reanalysis datasets to analyze the progression of the concurring warm, dry, and high fire risk conditions (i.e., dry compounds) since 1971. We show that the frequency of these compound extremes has surged in key South American regions including the northern Amazon, which have seen a 3-fold increase in the number of days per year with extreme fire weather conditions (including high temperatures, dryness, and low humidity). Our results also suggest that the surface temperature of the tropical Pacific Ocean modulates the interannual variability of dry compounds in South America. While El Niño enhances the fire risk in the northern Amazon, dry extremes in the Gran Chaco region appear to be more responsive to La Niña.

Phylogeny, historical biogeography and climate niche differentiation in extant species of Ceratophryidae (Anura, Hyloidea) frogs in South America

Ceratophryidae is a family of frogs containing twelve extant species distributed in South America. Several studies have been carried out concerning the systematics, morphology, karyotypes, and behaviour within this monophyletic family. However, little is known about the historical biogeography and the divergence in time of this group. Here, we present an updated phylogeny, along with a calibrated chronogram, to analyse the historical biogeographical pattern and climate niche differentiation among extant species of Ceratophryidae (Anura: Hyloidea) frogs in South America. A phylogeny based on morphological and genetic data was obtained from 256 morphological characters, six mitochondrial and eight nuclear genes for up to a total of 8428 characters in the homological matrix. Our results indicate that the genus Ceratophrys is sister to the clade Chacophrys + Lepidobatrachus. The divergence of the crown group of Ceratophryidae is estimated to have occurred 19.2 Ma at the beginning of the Miocene, with recent cladogenetic events related to the late Miocene (10.18–13.70 Ma) and the Pliocene (~5.3–2.6 Ma). Moreover, the Cerrado region is estimated to be the ancestral area of the family, as well for the genera Chacophrys and Lepidobatrachus. In addition, temperature seasonality and annual precipitation play a major role in the niche differentiation of extant species within Ceratophryidae. In conclusion, our data suggest multiple dispersal and vicariance events originating from the Cerrado region in the early Miocene, and recognize the role of the environment in the differentiation of the ecological niches among extant species of this family in South America. Ceratophryidae is hypothesized to have originated in the semi-arid Cerrado region in the early Miocene (~19.2 million years ago), from where species have diversified by independent dispersal and vicariance events across other South American regions. Ceratophrys frogs are phylogenetically recovered as the sister taxon to the clade comprising Chacophrys and Lepidobatrachus. Three lineages of Lepidobatrachus and four lineages from Ceratophrys diverged in the Pliocene, around 5.3 to 2.6 million years ago. Niche differentiation among extant species of Ceratophryidae appears to reflect roles for temperature seasonality and annual precipitation.

Risk Factors for Ovarian Cancer in South America: A Literature Review.

Background/Objectives: In 2020, ovarian cancer ranked fourth in global incidence among gynecological cancers and remains the deadliest cancer affecting women's health. Survival rates are significantly higher when the disease is detected at early stages; however, the lack of effective early detection methods underscores the importance of identifying risk factors in order to implement preventive strategies. The objective of this work is to provide an overview of the risk factors of ovarian cancer in South America, emphasizing those linked to social determinants, genetic components, and comorbidities. Methods: A literature search was performed using PubMed and Google Scholar. MeSH descriptors and keywords, such as "BRCA1 genes," "BRCA2 genes", "Latin America", and "ovarian neoplasms" were used, along with terms related to socioeconomic and health factors. Inclusion criteria focused on original studies published in the last five years involving South American women. Results: Studies were identified from Argentina, Brazil, Chile, Colombia, Ecuador, and Peru. These studies addressed genetic factors, health status at diagnosis, and sociodemographic factors, revealing important data gaps, particularly on contraception and hormone replacement therapy. The prevalence of BRCA1 and BRCA2 mutations in South America is estimated to be 15-20% among women with inherited risk factors. Social, demographic and economic factors vary by country, although commonalities include a higher prevalence among women over 50 years of age, those with limited education, and those who face barriers to accessing health care. Conclusions: Although the literature does not conclusively establish a direct link between obesity and/or diabetes and the development of ovarian cancer, the indirect association highlights the need for further clinical studies. A general research gap related to risk factors of ovarian cancer could be observed in the South American region.

On the Role of Physical Processes in Controlling Equatorial Plasma Bubble Morphology

AbstractIn this study, we present the results of an analysis of the morphological features of Equatorial Plasma Bubbles (EPBs) over South America. In this context, we analyzed data from the Disturbance Ionosphere indeX (DIX) maps calculated using around 450 Global Navigation Satellite System (GNSS) stations. To mitigate the influence of magnetic disturbances on bubble development, only data from geomagnetically quiet days were utilized. This study covered the period from the post‐peak of solar cycle 24 (2015) to the pre‐peak of solar cycle 25 (2023), totaling 1321 nights with EPB occurrences, representing the largest data set of EPBs ever compiled for South America. Our analysis unveiled several key findings regarding EPBs and their behavior over the South American region. First, we observed that the amplitude of plasma depletions, as reflected in the DIX values, and the EPB latitudinal development follow an approximately 11‐year cycle driven by solar radiation levels. Furthermore, our analysis highlights the significant influence of factors such as the angle between the solar terminator and the magnetic meridian (T‐M angle), which varies inversely with the vertical plasma drift velocity during the pre‐reversal enhancement (PRE). Additionally, we discuss the longitudinal variations associated with magnetic declination, as well as the saturation behavior of EPB development with extreme solar flux.

The Black Consciousness Movement in Azania (South Africa): A triple heritage

Starting with the 2015 Rhodes Must Fall campaign, there has been renewed interest in the philosophy of black consciousness through popular expressions – on social media and mainstream media articles – and by scholars. This article seeks to revisit the origins of the Black Consciousness Movement (BCM) in Azania (South Africa). Through an examination of primary sources, that is, documents written by the activist writers of the movement and secondary sources by scholars who reflect on the movement and other expressions of black resistance against colonialism and the oppression of black people globally, this article relies mainly on literature review of documents that are in the public domain. The overall findings of the review show that the BCM drew inspiration from and was shaped by the ‘black radical tradition’ influences from North America (specifically the United States), the Caribbean and South American region, and from the African continent, including locally in South Africa. While shaped by these influences the BCM adapted them and responded to the peculiarities of the condition of black people in South Africa and thus formulated a unique brand of black consciousness. The conclusion reached herein is that movements and the ideas that they espouse, are often confluences of views and practices drawn from different sources.Transdisciplinary Contribution: This article contributes to the understanding of the evolution of political movements from a variety of disciplines – political studies, history, sociology of ideas, history of consciousness and political philosophy.

Miscellaneous nomenclatural notes on Andean Chrysochlamys (Clusiaceae: Clusieae)

Chrysochlamys (Clusiaceae) is a strictly Neotropical genus that comprises between 35 and 55 species. The taxonomy of the genus is poorly-known in South American region, especially in Andean countries. During the taxonomic revision of Chrysochlamys and related genera in Colombia we observed two mainly gaps: the unclear nomenclatural history of Andean Chrysochlamys and the necessity of lectotypification of some species published by Pax, Poeppig, Planchon and Triana. To solve both issues, we provide a Chrysochlamys nomenclatural history summary and reduce nomenclatural ambiguities on a few Andean flora. For this, we carried out an exhaustive analysis of Chrysochlamys and related genera type collections and protologues. We propose a new combination, Chrysochlamys microcarpa comb. nov., originally published in Tovomita, designated six lectotypes, propose a numbering for three Triana’s type collections, and discuss a case of inadvertent lectotypification. This paper provides relevant information about problematic or understudied Chrysochlamys species, which will be useful for subsequent taxonomic studies.

Evaluation of Site Terms for Ground-Motion Models for South America

ABSTRACT The time-averaged shear-wave velocity in the top 30 m, VS30, is used to represent the site condition in many ground-motion models (GMMs). Regionalized GMMs account for regional differences in the ln(VS30) scaling by including region-specific coefficients for the site term. For example, recent GMMs developed for subduction zone earthquakes as part of the Next Generation Attenuation-Subduction (NGA-Sub) project include region-specific VS30 scaling for seven regions: South America, Central America, Japan, New Zealand, Taiwan, Cascadia (Pacific Northwest America), and Alaska. Of these seven regions, South America has the largest within-event standard deviation. One cause for the larger within-event standard deviation is a weaker relation between VS30 and the site term in South America compared to other regions. A cause for this weak correlation is that most of the VS30 values for the South American region in the NGA-Sub data set are based on proxies. The relation between VS30 and the site term improves significantly for periods less than 1 s if only stations with measured VS30 are considered, but the correlation is weak for periods greater than 1 s even for stations with measured VS30, indicating that, for the South America region, VS30 is not well correlated with the deeper shear-wave velocity profile that controls the long-period amplification. To improve the site terms for South America, we develop a model based on the horizontal-to-vertical spectral ratio (HVSR) from microtremors, similar to the approach used by Pinilla-Ramos et al. (2022) for California. The data set includes 660 recordings from 51 earthquakes recorded at 274 sites. The site-term model includes the period-dependent HVSR amplitude and the geometric mean of the average HVSR amplitude over the frequency band of 0.25 to 15 Hz. Including these two parameters reduces the standard deviation of site-specific site terms over the period range 0.3–3 s, with the largest reduction in the period range 1–2 s. This site-term model can be incorporated into subduction GMMs and implemented in probabilistic seismic hazard analyses for South America.

Study of the response of the upper atmosphere during the annular solar eclipse on October 14, 2023

A solar eclipse is a fascinating event that gives a unique opportunity to study the ionospheric characteristics in a controlled blockage of solar radiation. We present the upper atmosphere’s response, mostly F-layer, during the annular eclipse on October 14, 2023. This eclipse was mostly visible from the North and South American regions with a maximum obscuration of around 91%. We study the response of the ionospheric Total Electron Content (TEC) and the critical frequency of the F2 layer (f0F2) for three consecutive days (October 13 to 15, 2023) using ground and space-based techniques. We present the ionospheric response for a large area that covers the path of the solar eclipse of latitude and longitude range from 50°N to 10°S and 30°W to 150°W. For the ground-based observation, we use fifty-five International GNSS Service (IGS) stations and eleven Global Ionospheric Radio Observatory (GIRO) Digisonde stations that cover the annular and partial solar eclipse and are in the close vicinity of the annularity belt. We compute the vertical TEC (VTEC) and f0F2 from this database and check their temporal and spatial variations. It is found that the VTEC, as computed from the IGS stations, mostly shows decrements during the partial blockage of the sun by the lunar disc. The VTEC, as computed from the GIRO database, also shows a decreasing trend but with comparatively more oscillating in nature. The f0F2 shows a similar decreasing trend due to the solar eclipse. For space-based observation, we use the Swarm satellite data for the tracks that have gone through the annularity belt. Also, a spatiotemporal study is executed using the Global Ionospheric Map (GIM) database. For both cases, the VTEC shows a prominent depletion. We investigate the variation in the percentage change in VTEC as a function of obscuration and observe a positive correlation between them. We also compute the time difference between the maximum eclipse and the maximum TEC modulation to investigate the response time profiles of the ionosphere at different receiving stations. All the methods give satisfactory and consistent outcomes that corroborate the physical mechanism of ionospheric variabilities due to the effect of the solar eclipse. We check the geomagnetic condition to eliminate the scope of contamination and observe that their values are normal during the study.

Designing MOOCs in South America towards open and equitable education

This study utilizes a qualitative research design to investigate the design experiences of massive open online courses (MOOCs) instructors in South American academic institutions. It reveals that MOOC instructors are primarily motivated to teach MOOCs from their desire to make contributions to society (e.g., providing free and accessible MOOCs on emerging topics and demanding subjects) and experience innovative teaching and learning, as well as respond to their institutions’ call for MOOCs. These courses are designed to reach audiences who face linguistic, financial, and geographical disadvantages within South American regions. The findings of this study inform the need to develop more non-English MOOCs in a variety range of subject areas to provide access to a broader population and promote educational equity. This study further addresses the ambiguity of the relationship between OER and MOOCs. The findings indicate that though MOOC instructors in South America have not yet fully perceived the benefits of OER, many of them have successfully integrated OER into their MOOCs to make them more accessible.

The impact of the Hunga Tonga–Hunga Ha’apai volcanic eruption on the Peruvian atmosphere: from the sea surface to the ionosphere

The eruption of the Hunga Tonga Hunga Ha’apai volcano on 15 January 2022 significantly impacted the lower and upper atmosphere globally. Using multi-instrument observations, we described disturbances from the sea surface to the ionosphere associated with atmospheric waves generated by the volcanic eruption. Perturbations were detected in atmospheric pressure, horizontal magnetic field, equatorial electrojet (EEJ), ionospheric plasma drifts, total electron content (TEC), mesospheric and lower thermospheric (MLT) neutral winds, and ionospheric virtual height measured at low magnetic latitudes in the western South American sector (mainly in Peru). The eastward Lamb wave propagation was observed at the Jicamarca Radio Observatory on the day of the eruption at 13:50 UT and on its way back from the antipodal point (westward) on the next day at 07:05 UT. Perturbations in the horizontal component of the magnetic field (indicative of EEJ variations) were detected between 12:00 and 22:00 UT. During the same period, GNSS-TEC measurements of traveling ionospheric disturbances (TIDs) coincided approximately with the arrival time of Lamb and tsunami waves. On the other hand, a large westward variation of MLT winds occurred near 18:00 UT over Peru. However, MLT perturbations due to possible westward waves from the antipode have not been identified. In addition, daytime vertical plasma drifts showed an unusual downward behavior between 12:00 and 16:00 UT, followed by an upward enhancement between 16:00 and 19:00 UT. Untypical daytime eastward zonal plasma drifts were observed when westward drifts were expected. Variations in the EEJ are highly correlated with perturbations in the vertical plasma drift exhibiting a counter-equatorial electrojet (CEEJ) between 12:00 and 16:00 UT. These observations of plasma drifts and EEJ are, so far, the only ground-based radar measurements of these parameters in the western South American region after the eruption. We attributed the ion drift and EEJ perturbations to large-scale thermospheric wind variations produced by the eruption, which altered the dynamo electric field in the Hall and Pedersen regions. These types of multiple and simultaneous observations can contribute to advancing our understanding of the ionospheric processes associated with natural hazard events and the interaction with lower atmospheric layers.Graphical

Mayaro virus, a potential threat for Europe: vector competence of autochthonous vector species

BackgroundMayaro virus (MAYV) is an emerging alphavirus, primarily transmitted by the mosquito Haemagogus janthinomys in Central and South America. However, recent studies have shown that Aedesaegypti, Aedesalbopictus and various Anopheles mosquitoes can also transmit the virus under laboratory conditions. MAYV causes sporadic outbreaks across the South American region, particularly in areas near forests. Recently, cases have been reported in European and North American travelers returning from endemic areas, raising concerns about potential introductions into new regions. This study aims to assess the vector competence of three potential vectors for MAYV present in Europe.MethodsAedesalbopictus from Italy, Anophelesatroparvus from Spain and Culexpipiens biotype molestus from Belgium were exposed to MAYV and maintained under controlled environmental conditions. Saliva was collected through a salivation assay at 7 and 14 days post-infection (dpi), followed by vector dissection. Viral titers were determined using focus forming assays, and infection rates, dissemination rates, and transmission efficiency were calculated.ResultsResults indicate that Ae.albopictus and An.atroparvus from Italy and Spain, respectively, are competent vectors for MAYV, with transmission possible starting from 7 dpi under laboratory conditions. In contrast, Cx.pipiens bioform molestus was unable to support MAYV infection, indicating its inability to contribute to the transmission cycle.ConclusionsIn the event of accidental MAYV introduction in European territories, autochthonous outbreaks could potentially be sustained by two European species: Ae.albopictus and An.atroparvus. Entomological surveillance should also consider certain Anopheles species when monitoring MAYV transmission.Graphical abstract

Global paleobiogeography of Albian–Cenomanian (mid-Cretaceous) marine ostracods

Despite their potential for providing important information for paleobiogeography, studies using ostracod assemblages compiled from global datasets have been scarce so far. In this study, the paleogeographic implications of the relationship between different ostracod assemblages are analyzed and discussed for the Albian and Cenomanian. We compiled an ostracod dataset at the genus level, with 168 genera for the Albian and 174 for the Cenomanian, to which different multivariate statistical methods of grouping were applied. The affinity between different ostracod assemblages from different regions allowed for the delineation of 30 operational geographic units (OGUs) for the Albian, and 32 OGUs for the Cenomanian, grouped in three paleobiogeographic units (PBUs; Megatethys, Persia, and Austral) and one sub-unit (PBSU; Maghreb associated to the Megatethys). The Maghreb PBSU showed minor changes between the Albian and Cenomanian. The relationship among the OGUs grouped in each PBU is related to different factors, such as eustatic sea level events, similar climatic zones, and marine current circulation patterns. A relationship was observed between the Gabon and Nigeria OGUs with the Persia PBU, which suggests a direct east–west connection between them during the Cenomanian. The affinity observed in the Austral PBU between the South American, South African, and Australian regions during the Albian can be explained by their relative geographic isolation due to the Walvis Ridge barrier. The eventual flooding of this barrier led to the relationship observed between the SE Brazilian and Bolivian regions with the Austral PBU. Finally, the data also suggested that the separation of the Indian subcontinent from the Austral PBU took place during the Cenomanian.

3‐D Ionospheric Imaging Over the South American Region With a New TEC‐Based Ionospheric Data Assimilation System (TIDAS‐SA)

AbstractThis study has developed a new TEC‐based ionospheric data assimilation system for 3‐D regional ionospheric imaging over the South American sector (TIDAS‐SA) (45°S–15°N, 35°–85°W, and 100–800 km). The TIDAS‐SA data assimilation system utilizes a hybrid Ensemble‐Variational approach to incorporate a diverse set of ionospheric data sources, including dense ground‐based Global Navigation Satellite System (GNSS) line‐of‐sight Total Electron Content (TEC) data, radio occultation data from the Constellation Observing System for Meteorology, Ionosphere, and Climate‐2 (COSMIC‐2), and altimeter TEC data from the JASON‐3 satellite. TIDAS‐SA can produce a reanalyzed three‐dimensional (3‐D) electron density spatial variation with a high time cadence, yielding spatial‐temporal resolution of 1° (latitude) × 1° (longitude) × 20 km (altitude) × 5 min. This allows us to reconstruct and study the 3‐D ionospheric morphology with multi‐scale structures. The performance of the data assimilation system is validated against independent ionosonde and in situ measurements through an experiment for a strong geomagnetic storm event on 03–04 November 2021. The results demonstrate that TIDAS‐SA can provide detailed and altitude‐resolved information that accurately characterizes the storm‐time ionospheric disturbances in vertical and horizontal domains over the equatorial and low‐latitude regions of South America.

A Hybrid Deep Learning Algorithm for Tropospheric Zenith Wet Delay Modeling with the Spatiotemporal Variation Considered

The tropospheric Zenith Wet Delay (ZWD) is one of the primary sources of error in Global Navigation Satellite Systems (GNSS). Precise ZWD modeling is essential for GNSS positioning and Precipitable Water Vapor (PWV) retrieval. However, the ZWD modeling is challenged due to the high spatiotemporal variability of water vapor, especially in low latitudes and specific climatic regions. Traditional ZWD models make it difficult to accurately fit the nonlinear variations in ZWD in these areas. A hybrid deep learning algorithm is developed for high-precision ZWD modeling, which considers the spatiotemporal characteristics and influencing factors of ZWD. The Convolutional Neural Network (CNN) and Long Short-Term Memory (LSTM) are combined in the proposed algorithm to make a novel architecture, namely, the hybrid CNN-LSTM (CL) algorithm, combining CNN for local spatial feature extracting and LSTM for complex sequence dependency training. Data from 46 radiosonde sites in South America spanning from 2015 to 2021 are used to develop models of ZWD under three strategies, i.e., model CL-A without surface parameters, model CL-B with surface temperature, and model CL-C introducing surface temperature and water vapor pressure. The modeling accuracy of the proposed models is validated using the data from 46 radiosonde sites in 2022. The results indicate that CL-A demonstrates slightly better accuracy compared to the Global Pressure and Temperature 3 (GPT3) model; CL-B shows a precision increase of 14% compared to the Saastamoinen model, and CL-C exhibits accuracy improvements of 30% and 12% compared to the Saastamoinen and Askne and Nordius (AN) model, respectively. Evaluating the models’ generalization capabilities at non-modeled sites in South America, data from six sites in 2022 were used. CL-A shows overall better performance compared to the GPT3 model; CL-B’s accuracy is 19% better than the Saastamoinen model, and CL-C’s accuracy is enhanced by 33% and 10% compared to the Saastamoinen and AN model, respectively. Additionally, the proposed hybrid algorithm demonstrates a certain degree of improvement in both modeling accuracy and generalization accuracy for the South American region compared to individual CNN and LSTM algorithm.

Cost, time and environmental impact in the execution of mine closure coverage with geosynthetics

Between 10 and 20 years have passed in which several countries of the South American region began declaration processes of mine closures to the respective countries in which mining companies operate. Several of these declared projects initiates actual closure processes, in dumps, tailings deposits, leaching pads, and pits. During the closure process with the use only of granular and cohesive materials; it has been observed that its extraction and placement have presented serious problems of excessive costs, lack of availability, long execution times and environmental problems due to the process of closing the borrow material areas used. This leads to observe if improvements can be made in this type of projects with the use of Geosynthetics. After more than 30 years of using geosynthetics in mining operation projects in South America, they have shown that they can be more efficient in cost and time, in addition to providing less impact benefits when used. In papers presented at other conferences on the design methodology of mine closure covers with geosynthetics, as well as methodologies for estimating the durability, they have left a precedent for their applicability and how to design them as a substitute for soils in this type of project. Experiences of coverages built following these methodologies available up to date have also been presented in congresses. This work focuses on making economic comparisons obtained by using geosynthetics in mine closure covers, as well as the time savings that can be obtained with the benefits of high quality installation using geosynthetics. The issue of impact generated by the lower consumption of fossil fuel and borrow material sites that will later require more closing work is also focused. Comparisons of these issues are presented, in order to share information to designers, project managers and environmental officials who have to deal with mine closure covers.