South America Research Articles

3D Shear Velocity Structure of the Caribbean—Northwestern South America Subduction Zone From Ambient Noise and Ballistic Rayleigh Wave Tomography

3D Shear Velocity Structure of the Caribbean—Northwestern South America Subduction Zone From Ambient Noise and Ballistic Rayleigh Wave Tomography

Forage yield and nutritive value of plantain and chicory for livestock feed at high altitudes in Peru

AbstractBackgroundEvaluation of forage resources is vital for the sustainability of livestock farming in the South American Andes, especially under conditions of low water availability for irrigation and acid soils.MethodsWe evaluated the productivity and nutritive value of two cultivars of chicory (Cichorium intybus L.) and one of plantain (Plantago lanceolata L.) in three high‐altitude sites (AL) of the northern highlands of Peru: AL‐I: 2300–2800 m.a.s.l, AL‐II: 2801–3300 m.a.s.l. and AL‐III: 3301–3800 m.a.s.l., for 1 year. The parameters evaluated were dry matter yield (DMY), plant height (PH), growth rate (GR) and nutritional value.ResultsPlantain achieved the greatest annual DMY (ADMY), PH and GR compared to the two chicory cultivars (9.34, 9.56 and 13.39 Mg ha−1 for Puna II and Sese 100 chicory and Tonic plantain, respectively; p = 0.0019). The greatest ADMY and GR occurred at AL‐I. Regarding nutritional value, differences were observed only for in vitro digestibility of dry matter and metabolisable energy with chicory cultivars higher than plantain.ConclusionsThe results indicate that the three cultivars evaluated may be used as a nutritional supplement in cattle feed, associated with grasses because they have high nutritive value suitable for milk production in the mountain regions of Peru.

Impacts of AMOC Collapse on Monsoon Rainfall: A Multi‐Model Comparison

AbstractA collapse of the Atlantic Meridional Overturning Circulation (AMOC) would have substantial impacts on global precipitation patterns, especially in the vulnerable tropical monsoon regions. We assess these impacts in experiments that apply the same freshwater hosing to four state‐of‐the‐art climate models with bistable AMOC. As opposed to previous results, we find that the spatial and seasonal patterns of precipitation change are remarkably consistent across models. We focus on the South American Monsoon (SAM), the West African Monsoon (WAM), the Indian Summer Monsoon (ISM) and the East Asian Summer Monsoon (EASM). Models consistently suggest substantial disruptions for WAM, ISM, and EASM with shorter wet and longer dry seasons (−29.07%, −18.76%, and −3.78% ensemble mean annual rainfall change, respectively). Models also agree on changes for the SAM, suggesting rainfall increases overall, in contrast to previous studies. These are more pronounced in the southern Amazon (+43.79%), accompanied by decreasing dry‐season length. Consistently across models, our results suggest a robust and major rearranging of all tropical monsoon systems in response to an AMOC collapse.

Maritime Disputes from a Global Perspective and Solutions under International Law

This study explores the utilization and challenges of international laws in resolving global maritime disputes through a detailed analysis of representative cases from South America, Africa, and Asia. It highlights the crucial role of international law, particularly the United Nations Convention on the Law of the Sea (UNCLOS), in providing a legal framework and dispute resolution mechanisms. However, the study also identifies significant challenges, including political interference, legal ambiguity, and enforcement issues. By comparing regional dispute settlement mechanisms, the study demonstrates the effectiveness of multilateral negotiations in South America, regional legal frameworks in Africa, and a combination of multilateral and unilateral actions in Asia. Based on these insights, the study proposes several recommendations to enhance the international legal framework, promote regional cooperation, and innovate dispute resolution mechanisms. These measures aim to ensure fair and effective resolution of maritime disputes, maintain maritime peace and stability, and promote the healthy development of global ocean governance.

The Impact of Transportation on The Avocado Market in Tanzania

Avocado (Persea americana) is grown in many nations throughout Africa, Asia, Europe, and South America. The climate of Tanzania offers a perfect habitat for growing avocados. This paper investigates how transportation affects the Tanzanian avocado industry. Data were gathered from 505 farmers and 37 categories/groups using a cross-sectional design. Data analysis was done using SPSS where descriptive statistics and the chi-square test. A one-way analysis of variance (ANOVA) with Tukey's Honest Significant Difference (HSD) test at p < 0.05 was also done. According to the results, local avocado output is dominated by men (79% male vs. 21% female). The result of the binary logit model revealed that the participation of avocado producers in a high-value market was influenced by age, educational status, the number of avocados sold, the price of avocado, and market information. With sorting (12%), grading (7%), and packaging (9%), quality during production was judged most important (25%), followed by harvesting (16%), storage (16%), and transportation (15%) with less relevance were factors impacting quality. Improving the avocado market for growers depends on addressing these problems at the national, regional, and district levels. Hence, transportation has a big influence on the avocado industry since smallholder growers have great difficulties influencing market access and produce quality. Improvement of transport infrastructure and support systems at the national, regional, and district levels will help to boost the avocado market.

Variability of Winter Frosts in Central South America: Quantifying Mechanisms with Decision Trees

AbstractAgricultural production in Central South America (CSA) is substantially influenced by frost events. This study characterises and quantifies the physical processes leading to frost conditions in CSA from 1979 to 2022, focusing on three innovative aspects: regional frost properties, a novel multi-parametric upper-level jet description, and the quantification of underlying mechanisms through decision trees (DTs). The regionalisation analysis identifies five homogeneous frost regions in CSA. In all regions, the events tend to occur more frequently during the La Niña phase. Moreover, a significant increase in the frequency of widespread frost events has been observed in the Argentinean Pampas during the study period, primarily due to negative trends in minimum temperatures. Furthermore, the synoptic mechanisms triggering frosts, such as cold fronts and post-frontal anticyclones enhanced by subsidence near the subtropical jet (STJ) entrance, have not shown major long-term changes. To describe the jets, we compute six parameters for the STJ and seven for the polar front jet, including latitude, intensity, height, tilting, longitudinal extent, and branch number. DTs are used to identify key jet parameters linked to frost events, such as the latitude, longitudinal extent, and tilt of the Atlantic STJ. Frost likelihood increases when the STJ is north of 31°S, and the extension of the Atlantic STJ is longer than 35° and has a negative tilt. Finally, DTs focused on the onset and end of events highlight geopotential height anomalies and STJ extension as critical variables. These DTs provide concise and accessible information for agricultural decision-makers in CSA.

Daily variation and repeatability of advertisement calls in an austral temperate forest frog under controlled conditions

AbstractEstimating repeatability allows a first approximation that may indicate a potential response to selection of sexual traits. Acoustic sexual signals comprise spectral and temporal variables, where the former generally have lower intra‐individual variation and higher repeatability values. Studies of repeatability in anurans have been conducted mainly in natural conditions, but the stability of laboratory settings allows extended recording intervals, favoring measurement accuracy. We conducted a study of variation and repeatability of the calls of males of Batrachyla taeniata, a frog from the South American temperate forest to evaluate under homogeneous environmental and social conditions: (i) the extent of variation in acoustic properties of calls within and among days, (ii) the extent of temporal variation in the repeatability of call properties, and (iii) differences in repeatability among call variables. Variation of acoustic properties differed within and across days of recording, call rate generally increased within and throughout days, suggesting sensitization processes. Call duration decreased during these time spans, yielding constant calling effort. In contrast, the dominant frequency decreased within days but increased across days. Overall repeatability differs significantly among variables: dominant frequency, call rate, and call duration having the highest, intermediate, and lowest values, respectively. The high repeatability of call rate relative to call duration contrasts with an opposing general tendency in previous studies in anurans. The repeatability of the three variables analyzed increases within days, and the repeatability of call rate also increases throughout days, highlighting the relevance of this variable for individual identity over different time ranges.

Institutional dynamics in higher education in South America: An exploration of university mergers and acquisitions

Institutional dynamics in higher education in South America: An exploration of university mergers and acquisitions

Mortality in Patients with 22q11.2 Rearrangements.

The 22q11.2 region is highly susceptible to genomic rearrangements leading to multiple genomic disorders, including 22q11.2 microdeletion syndrome (22q11.2 DS) (MIM# 188400), 22q11.2 microduplication syndrome (MIM# 608363), supernumerary der(22)t(11;22) syndrome (also known as Emanuel Syndrome; MIM# 609029), and Cat Eye Syndrome (MIM# 115470). In this study, we present data on causes of mortality, average age of death, and the existing associated risk factors in patients with 22q11.2 rearrangements. Our cohort included 223 patients (120 males and 103 females) with confirmed diagnoses of 22q11.2 rearrangements diagnosed through molecular techniques (FISH, MLPA, and CMA). Relatives from patients who have been molecularly confirmed with 22q11.2 rearrangements have also been added to the study, regardless of the presence or absence of symptoms. Of these 223 individuals, 21 (9.4%) died. Deceased patients' rearrangements include 19 microdeletions, 1 microduplication, and 1 patient with a marker chromosome. The median age of death was 3 months and 18 days (ranging from 3 days to 34 years). There were 17 patients who died at pediatric age (80.95%), 3 died at adult age (14.28%), and for 1 of whom, the age of death is unknown (4.76%). Eighteen patients were White Mediterranean (European non-Finnish) (85.71%) whereas three were Amerindian (South American) (14.28%). Mortality from cardiac causes accounted for 71.42%. The second most frequent cause of death was sepsis in two patients (9.52%). One patient died from respiratory failure (4.76%) and one from renal failure (4.76%). Information regarding the cause of death was not available in two patients (9.52%). Most patients who died were diagnosed within the first week of life, the majority on the first day. This study adds additional information on mortality in one of the largest cohorts of patients with 22q11.2 rearrangements in more than 30 years of follow-up.

Mosasaur (Reptilia, Mosasauridae) remains from the Upper Cretaceous of Colombia, including the first occurrence of the genus Globidens

Isolated mosasaur teeth and vertebrae recovered from beds of the Guadalupe Group of central Boyacá, Colombia, are reported. A partial tooth crown identified as Globidens sp., found in the Labor-Tierna Formation (Maastrichtian), represents the first report of this genus from northern South America and its most equatorial occurrence. A tooth crown recovered from the Plaeners Formation (upper Campanian–lower Maastrichtian), represents the youngest record of the subfamily Plioplatecarpinae in Colombia. These occurrences collectively constitute the youngest record of the family Mosasauridae in Colombia and expand both the taxonomic diversity and biogeography of mosasaurids in northern South America.

Pesticides in Latin American and Caribbean freshwater: a critical review

Pesticides used in food production contaminate freshwater ecosystems. We present a critical analysis of pesticide use in Latin America and the Caribbean (LAC) from 1990 to 2020 and a systematic review of scientific literature about the presence of pesticides in freshwater, encompassing studies published from 1990 to 2023. Data were collected from FAOStat, PubMed, ScienceDirect, Scopus, and Google Scholar. Brazil was the primary pesticide user, with an annual consumption of 231,621 t, followed by Argentina (132,255 t) and Colombia (52,553 t). In 2020, LAC had the highest rate of pesticide application globally, with Ecuador leading at 13.74 kg/ha. South America dominates the total amount with 90.9% of pesticide use, primarily herbicides (51.5%), while pesticide usage in North and Central America, as well as the Caribbean, varied due to differing agricultural practices. The study examined 221 records for 26 out of 51 countries in the literature, highlighting the significant lack of information from numerous countries. Argentina, Mexico, and Brazil had the highest publication rates. Rivers, streams, and lakes (37%, 20%, and 12%, respectively) were the most commonly studied systems, and research focused mainly on pesticide concentration in water (46%), sediments (27%), and aquatic biota (15%). The imbalance between pesticide usage and monitoring in freshwaters leads to concerns about the awareness of ecological risk. Therefore, there is an urgent need for increased research on environmental monitoring in LAC to better understand pesticide impacts on these vital ecosystems.

Extrahepatic intraabdominal hydatid cyst: a case report

BackgroundHydatid disease, also known as echinococcosis, is a zoonotic parasitic infection caused by the larvae of the Echinococcus tapeworm. It is endemic in various regions worldwide, particularly in rural areas of countries in southern South America, Central Asia, China, parts of Africa, the Mediterranean, and parts of the Middle East. The disease primarily affects the liver (60–70% of cases) and the lungs (10–25% of cases), but it can involve any organ, including the brain, bones, and rarely the pelvic region, as seen in our case report. Hydatid disease typically follows an asymptomatic course in the early stages of the primary infection and may remain so potentially for years or even permanently. If symptoms occur, they depend on various factors, such as the number, size, and location among other factors. Typically, hydatid disease presents with nonspecific symptoms. Common symptoms include abdominal pain, hepatomegaly, as well as anaphylaxis in case of cyst rupture. Extrahepatic intra-abdominal isolated hydatic cyst is a rare finding (6–11%).Case presentationIn our case, a 70 year-old Asian white male presented with right thigh pain radiating to the lower leg, which is an atypical presentation for an extrahepatic intraabdominal hydatid cyst. Primary intraabdominal hydatid cysts involving the pelvic region are relatively rare, and such cases pose diagnostic and management challenges.ConclusionThis case report underscores the challenges in diagnosing and managing extrahepatic intraabdominal hydatid cysts, particularly in atypical presentations. A combination of clinical evaluation, serological studies, and imaging techniques facilitates accurate diagnosis.

Genetic structure and climate niche differentiation among populations of Leopardus geoffroyi.

Geoffroy's cat (Leopardus geoffroyi) is a small-sized felid native to South America. Given the species' distribution covering a wide variety of habitats, and the presence of high levels of anthropization in part of its range, it is possible that genetically differentiated groups exist and that they occupy different climatic niches. We assessed patterns of contemporary genetic diversity and structure in the species across most of its range, characterizing each inferred genetic group based on ecological niche models. We genotyped 11 microsatellites for 142 samples covering most of Geoffroy's cat distribution, and investigated patterns of genetic structure and diversity, applying spatial and nonspatial Bayesian clustering methods and a spatial principal component analysis. We created ecological niche models for each genetic cluster, evaluating whether these clusters occupy different climatic spaces and display differences in the suitability of different values of the climatic variables analyzed. We identified two genetic clusters, one in the north-northeast and the other in the south-southwest of the species' distribution. These clusters showed moderate FST values between them and differences in dispersal/genetic diversity. We found isolation-by-distance patterns globally and within each cluster. We observed lower expected heterozygosity compared with other studies and a north-south gradient in allelic richness. The southern cluster showed lower genetic variability and a more restricted climatic niche suggesting that this group is more vulnerable to the effects of the current context of climate change. Individuals from the southern genetic cluster are under different pressures, likely a product of the particularly dry habitat they occupy. Climatic variables associated with habitat suitability suggest the southern cluster has affinity for the arid and semiarid conditions present in its distribution. Conservation measures should consider the genetic structure observed and differences in climatic spaces to maintain the evolutionary potential of the species.

Massive offerings of marine fish at Salango, coastal Ecuador, during the Middle Guangala phase (AD 300–600)

The Ecuadorian site of Salango, with its 5500 years of pre-Columbian history, is of fundamental interest for understanding the relationships between people and the sea on the tropical Pacific coast of South America. In 2015, thousands of fish remains were found in foundational offering deposits of a perimeter wall built to protect a sanctuary of the Middle Guangala phase (AD 300–600). Approximately 3300 bones have been identified, and these represent the remains of 337 individuals belonging to 49 different species. The assemblage is largely dominated by pelagic species, particularly scombrids weighing 2–3 kg. The presence of dolphinfish, a taxon that has not been reported previously in the archaeological record of Salango, supports the hypothesis that fishing was mainly conducted offshore by boat. The preservation in situ of numerous anatomical connections and the large number of remains found virtually intact suggest that these fish were deposited whole. We suggest that these deposits were designed to represent the specific marine environment being exploited from Salango and, more broadly, the sea itself. In this respect, Salango presents an unusual manifestation of pre-Columbian sea-oriented ritual practice so far unique on the Ecuadorian coast.

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.

New chondrichthyan remains from the Devonian of Brazil and their implication for Devonian vertebrate distribution

ABSTRACT The mysterious scarcity of ‘fish’ in an extensive epicontinental sea has always intrigued countless researchers who worked with the South American Devonian, especially in the Malvinoxhosan (= Malvinokaffric) Paraná Basin. This scarcity is probably related to taphonomic factors and/or lack of experience of collectors with fossil ‘fish’. Currently, the vertebrate record of the Devonian of the Paraná Basin is restricted to three chondrichthyan fin fragments and an actinopterygian mandible. Here we describe the first ‘fish’ fossils from the northwest edge of the Paraná Basin, represented by Chondrichthyan fin spine, scales, and teeth, consisting in the oldest Devonian ‘fish’ in the basin, attributed to the Pragian-Emsian of Mato Grosso do Sul state. The morphology of the fin-spine is consistent with a stem chondrichthyan morphotype, and the teeth bear resemblance in cusp morphology to those of the protacrodontid type. Despite the low taxonomic refinement, this new record in the Devonian of the Paraná Basin shows the presence of ‘fish’ throughout the Basin already in the late Pragian – early Emsian. This is relevant, because the Paraná Basin is an important region for better understanding the distribution of the South American Devonian vertebrate fauna through time and space.

Moho depth model of South America from a machine learning approach

Crustal structure models play an important role in the characterization of seismogenic zones, in the regional delimitation of geological provinces and particularly, in understanding the genesis and evolution of sedimentary basins. Despite the increasing number of new seismic surveys and seismographic networks in South America, crustal thickness measurements are still scarce and irregularly sampled, reducing the resolution of crustal model maps. To overcome these challenges, a novel approach based on machine learning techniques is proposed, in order to explore higher resolution gravity datasets in the interpolation of crustal thickness measurement points obtained from previous seismic/seismological compilations. The algorithm used in this study is based on Gaussian processes prediction methods, which allowed inferring the depth of Moho to South America. The prediction error of the model obtained from the training and testing database was 3.48 km, which is compatible with the uncertainties derived from the H-k stacking analysis. The depth range varied from 69.8 km beneath the Andes to 4.3 km in oceanic regions. The average Moho depth for the South American Platform is 39.1 km, allowing a spatial correlation of deeper and shallower Moho regions with different types of continental basins. Compared to other models, the model resulting from this study presents fine-scale features highlighting the limits of the main tectonic domains and a good agreement with the suture zones. Overall, this study demonstrates the potential of applying machine learning tools in crustal-scale imaging using sparse datasets, providing new advances in Moho modeling of the South America, as well as new perspectives on its the history and tectonic evolution.

Fatal journeys: causes of death in international travellers in South America.

Understanding mortality among travellers is essential for mitigating risks and enhancing travel safety. However, limited evidence exists on severe illnesses and injuries leading to death among travellers, particularly in low- and middle-income countries and remote regions. We conducted a retrospective census study using country-level observational data from death certificates of travellers of seven South American countries (Argentina, Brazil, Chile, Colombia, Ecuador, Peru, and Uruguay) from 2017 to 2021. Causes of death were evaluated using ICD-10 codes, categorised into non-communicable diseases (NCDs), communicable diseases, and injuries. We quantified causes of death by demographic characteristics (e.g. age, sex), and geographical variables. Chi-square tests were used to assess differences between categories. We calculated crude mortality rates and incidence rate ratios (IRRs) per country's subregions. A total of 17 245 deaths were reported. NCDs (55%) were the most common cause of death, followed by communicable diseases (23.4%) and injuries (18.1%). NCD-associated deaths increased after age 55years and were highest among ≥85years. Communicable diseases were more common at younger age (<20years). Injury-associated deaths were more common in men (79.9%) and 25-29-year-olds (17.1%). Most deaths (68.2%) could have been avoided by prevention or treatment. Mortality risk was higher among travellers in bordering regions between countries. In Roraima [Brazil] and Norte de Santander [Colombia], locations bordering Venezuela, the death incidence rate ratio was 863 and 60, respectively. These countries' reference mortality rates in those regions were much lower. More than 80% of the deaths in these border regions of Brazil and Colombia involved Venezuelan citizens. Conclusion: The study identified risk factors and high-risk locations for deaths among travellers in seven countries of South America. Our findings underscore the need for specific health interventions tailored to traveller demographics and destination to optimise prevention of avoidable deaths in South America.

Assessing abundance-suitability models to prioritize conservation areas for the dwarf caimans in South America.

Species-environment relationships have been extensively explored through species distribution models (SDM) and species abundance models (SAM), which have become key components to understand the spatial ecology and population dynamics directed at biodiversity conservation. Nonetheless, within the internal structure of species' ranges, habitat suitability and species abundance do not always show similar patterns, and using information derived from either SDM or SAM could be incomplete and mislead conservation efforts. We gauged support for the abundance-suitability relationship and used the combined information to prioritize the conservation of South American dwarf caimans (Paleosuchus palpebrosus and P. trigonatus). We used 7 environmental predictor sets (surface water, human impact, topography, precipitation, temperature, dynamic habitat indices, soil temperature), 2 regressions methods (Generalized Linear Models-GLM, Generalized Additive Models-GAM), and 4 parametric distributions (Binomial, Poisson, Negative binomial, Gamma) to develop distribution and abundance models. We used the best predictive models to define four categories (low, medium, high, very high) to plan species conservation. The best distribution and abundance models for both Paleosuchus species included a combination of all predictor sets, except for the best abundance model for P. trigonatus which incorporated only temperature, precipitation, surface water, human impact, and topography. We found non-consistent and low explanatory power of environmental suitability to predict abundance which aligns with previous studies relating SDM-SAM. We extracted the most relevant information from each optimal SDM and SAM and created a consensus model (2,790,583 km2) that we categorized as low (39.6%), medium (42.7%), high (14.9%), and very high (2.8%) conservation priorities. We identified 279,338 km2 where conservation must be critically prioritized and only 29% of these areas are under protection. We concluded that optimal models from correlative methods can be used to provide a systematic prioritization scheme to promote conservation and as surrogates to generate insights for quantifying ecological patterns.

A scoping review of websites for forensic odontology training programs.

Forensic Odontology developed as a discipline in 1898 with the publication of its first textbook; however, 126 years later, a standardised core curriculum for formal training in Forensic Odontology has yet to be decided. This website scoping review aims to provide information on three main distinct categories (and 17 subcategories): Availability, Content, and Quality of Forensic Odontology education globally. The information on formal education programmes was gathered by conducting a web search using 'Google Search' in English, Arabic, Spanish, and French languages between June and July 2022. Fifty-six programmes from 18 countries met the inclusion criteria. Of the 14 master's and 42 diploma programmes, only 7.14% provided information on their websites from all the subcategories investigated. The highest numbers of master's and postgraduate diploma programmes were identified in Europe (18 programmes), South America (15), North America (11) and Asia (7). A practical aspect was included by 10 master's and 12 diploma programmes' websites. Research integration in various forms was included by 11 master's and seven diploma programmes. Programme providers and applicants must critically consider the quality of the programme being designed or applied to as there are currently no international training standards in Forensic Odontology. This study has developed an 'International Database of Forensic Odontology Programmes' (IDFOP).