South America Research Articles

Duration Models for Subduction Earthquakes

ABSTRACT An empirical model for the significant duration of acceleration for subduction zone earthquakes is developed based on the normalized Arias intensity. The data set is a subset from the Next Generation Attenuation-Subduction database (Bozorgnia and Stewart, 2020). The functional form of the duration model uses an additive model for the source, path, and site terms with three lognormally distributed random effects for the source, path, and site. The remaining aleatory variability is modeled by a power-normal distribution. There are two parts of the duration model: a model for the D5–75 duration and a model for the D5–X/D5–75 ratio, which can be combined with the D5–75 model to estimate the DY–X for any interval. The D5–75 model includes regionalized coefficients for Japan, New Zealand, South America, and Taiwan. The large-magnitude (M >7) scaling of the D5–75 model is much weaker than the recent duration model by Bahrampouri et al. (2021). The residuals of the D5–75 model are negatively correlated with the lnPGA residuals with a correlation coefficient of −0.50 such that above-average peak ground acceleration values are associated with below-average duration values.

Abstract A050: Early detection of liver cancer from diverse populations using cfDNA fragmentome and protein biomarkers

Abstract Hepatocellular carcinoma (HCC) is a leading cause of cancer death world-wide. In the US, liver cancer has increased in incidence and mortality due to a growing population from South and Central America, which faces higher risk of disease in part due to aflatoxin exposure. Recently, we showed that the DELFI (DNA evaluation of fragments for early interception) approach using genome-wide cell free DNA (cfDNA) fragmentation profiles and machine learning can be used for detection of liver and other cancers. Having previously demonstrated that a DELFI classifier accurately detects HCC in populations from the US and Hong Kong, we evaluated the classifier in other clinically relevant cohorts worldwide. Here we show that approach generalizes to diverse populations, and that including other genomic and protein features from the same blood draw improves performance. We examined plasma samples from 377 individuals, including 244 individuals with HCC and 133 without cancer, including 85 with cirrhosis. Plasma samples were collected from individuals with or without HCC in a case-control study in Guatemala (n=203) and from a prospective collection in Romania (n=174) and cfDNA was analyzed by whole- genome sequencing at ∼10x coverage. The median DELFI scores using a locked classifier (Foda et al., Cancer Discovery, 2023) were higher in both cohorts for patients with cancer across all stages compared to individuals without cancer, regardless of the presence of cirrhosis. Using the locked model with a threshold that corresponded to 80% specificity in prior work, DELFI detected individuals with HCC with sensitivities of 90% and 69% in the two cohorts at specificities of 92% and 86%, respectively. For early-stage HCC within Milan Criteria for liver transplantation, sensitivities were 85% in the case-control cohort and 64% in the prospective cohort. In these cohorts, the fixed DELFI model outperformed AFP at the clinically used threshold of 20 ng/mL with a sensitivity in the combined cohorts of 78% at 91% specificity, compared to 63% sensitivity at 91% specificity for AFP. A combined approach using either DELFI at a threshold that corresponded to a 90% specificity in our previous study or AFP at the clinical threshold resulted in 82% sensitivity (74% in early stage) at 92% specificity and was superior to estimates of AFP and ultrasound for early-stage disease (63% sensitivity at 84% specificity). Individuals who tested positive with DELFI had a significantly shorter overall survival (p=0.002, log rank test), even amongst individuals at the earliest stage, while AFP alone did not stratify survival for patients with early-stage disease. Single-molecule analyses from low coverage WGS of cfDNA revealed genome-wide mutational profiles that were similar to those of HCC and in individuals from Guatemala that were characteristic of aflatoxin exposure. Overall, this work provides insight into the origins of cfDNA in populations at risk for HCC and validates our genome-wide fragmentome approach for non-invasive cancer detection that may facilitate liver cancer screening. Citation Format: Zachariah H Foda, Daniel Bruhm C Bruhm, Akshaya V Annapragada, Shashikant Koul, Sarah Short, Keerti Boyapati, Adrianna Bartolomucci, Vilmos Adleff, Nicholas A Vulpescu, Hope Orjuela, Andrei Sorop, Razvan Iacob, Liana Gheorghe, Simona Dima, Katherine A McGlynn, Manuel Ramírez-Zea, Jillian Phallen, John Groopman, Robert B Sharpf, Victor E Velculescu. Early detection of liver cancer from diverse populations using cfDNA fragmentome and protein biomarkers [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A050.

Performance evaluation of UKESM1 for surface ozone across the pan-tropics

Abstract. Surface ozone monitoring sites in the tropics are limited, despite the risk that surface ozone poses to human health, tropical forest and crop productivity. Atmospheric chemistry models allow us to assess ozone exposure in unmonitored locations and evaluate the potential influence of changing policies and climate on air quality, human health and ecosystem integrity. Here, we utilise in situ ozone measurements from ground-based stations in the pan-tropics to evaluate ozone from the UK Earth system model, UKESM1, with a focus on remote sites. The study includes ozone data from areas with limited previous data, notably tropical South America, central Africa and tropical northern Australia. Evaluating UKESM1 against observations beginning in 1987 onwards, we show that UKESM1 is able to capture changes in surface ozone concentration at different temporal resolutions, albeit with a systematic high bias of 18.1 nmol mol−1 on average. We use the diurnal ozone range (DOR) as a metric for evaluation and find that UKESM1 captures the observed DOR (mean bias of 2.7 nmol mol−1 and RMSE of 7.1 nmol mol−1) and the trend in DOR with location and season. Results from this study reveal that hourly ozone concentrations from UKESM1 require bias correction before use for impact assessments based on human and ecosystem health. Indeed, hourly surface ozone data have been crucial to this study, and we encourage other modelling groups to include hourly surface ozone output as a default.

A systematic workflow of data mining confirms widespread ecological risks of SDHIs fungicides contamination in aquatic environment.

Succinate dehydrogenase inhibitors (SDHIs) are widely utilized fungicides that have been detected in various environments, raising significant concerns regarding their toxicity to aquatic organisms. A comprehensive analysis of SDHIs contamination and associated ecological risks has been challenging due to scattered data and varying scale. This study consolidated residue data from 194 aquatic environments across six regions, up to June 2024, providing an overview of SDHIs distribution and conducting a global-scale aquatic ecological risk assessment. We analyzed 20 SDHIs, with boscalid, fluopyram, flutolanil, fluxapyroxad, mepronil, and thifluzamide being the most frequently detected across Asia, Europe, North America, South America, Africa, and Australia. The concentrations and types of SDHIs varied significantly among continents, with data sourced from water, sediment and aquatic organisms. Utilizing a web-based Interspecies Correlation Estimation-Species Sensitivity Distribution (ICE-SSD) model, we identified substantial sensitivity differences among species, with benzovindiflupyr showing the lowest LC50 of 3.5 μg/L, indicating a high risk when concentrations exceed 0.035 μg/L (Maximum Acceptable Concentration, MAC). Risk quotient (RQ) values revealed that flutolanil posed high risks to eight aquatic ecosystems and medium risks to five, while boscalid presented medium risk to one ecosystem. Our findings also demonstrated a significant correlation between the aquatic ecotoxicity of SDHIs and their characteristics (log Kow, solubility, and pKa). Collectively, we advocate for the restricted use of SDHIs and emphasize the necessity for further evaluation of their environmental behavior and integrated risks within the "One Health" framework.

Trading Community Analysis of Countries’ Roll-On/Roll-Off Shipping Networks Using Fine-Grained Vessel Trajectory Data

Roll-on/roll-off vessels (RO/RO vessels) are playing an increasingly critical role in international automobile transport, facilitating the efficient movement of vehicles and heavy machinery across continents. Despite this growing significance, there is still limited research specifically focused on the RO/RO shipping network and its impact on global trade. This paper studies the global RO/RO shipping network using AIS data on RO/RO vessels collected from 2020 to 2023. We construct a method based on the complex network theory and the graph feature extraction method to quantitatively assess the features of the RO/RO shipping network. This method assesses the complexity, sparsity, homogeneity, modularity, and hierarchy of the RO/RO shipping network across various ports and countries and employs the graph convolutional neural network (GCN) model to extract network features for community detection. This process enables the identification of port clusters that are frequently linked to RO/RO vessels, as well as regional transport modes. The paper’s findings support these conclusions: (1) From 2020 to 2023, the number of nodes in the RO/RO shipping network increased by 22%, primarily concentrated in African countries. The RO/RO shipping network underwent restructuring after the pandemic, with major complex network parameters showing an upward trend. (2) The RO/RO shipping network is complex, with a stable graph density of 0.106 from 2020 to 2023. The average degree increased by 7% to 4.224. Modularity decreased by 6.5% from 0.431 in 2022 to 0.403, while the hierarchy coefficient rose to 0.575, suggesting that post-pandemic, community routes have become more diverse, reflecting the reconstruction and maturation of the overall network. (3) The model yielded a silhouette coefficient of 0.548 and a Davies–Bouldin index of 0.559 using an improved automatic feature extraction method. In comparison between 2020 and 2023, the changes in the two indicators are small. This shows that GINs can effectively extract network features and give us results that we can understand for community detection. (4) In 2023, key communities divide the RO/RO shipping network, with one community handling 39% of global routes (primarily Europe–Asia), another community handling 23% (serving Asia–Pacific, Africa, and the Middle East), and a third community managing 38% (linking Asia, Europe, and South America).

Linking Biodiversity and Functional Patterns of Estuarine Free-Living Nematodes with Sedimentary Organic Matter Lability in an Atlantic Coastal Lagoon (Uruguay, South America)

We examined the taxonomical and functional traits of free-living nematodes, focusing on their density by genus, maturity index (MI), and trophic diversity index (ITD) to determine whether these indices are sensitive to changes in the organic content of the sediment. Samples were collected in autumn and spring from 12 subtidal sampling stations in Rocha Lagoon, distributed between the outer (near the mouth) and the inner sector. We identified 26 genera, with higher abundance in the inner sector, likely due to increased organic matter and biopolymers. In spring, both sectors had sediments rich in fresh organic matter, dominated by deposit-feeding nematodes and showing low trophic diversity (high ITD values). In autumn, the inner sector maintained similar characteristics to spring sampling, while the outer one was dominated by older organic matter, predatory nematodes and higher trophic diversity. The MI showed low variation between sectors, suggesting a disturbed environment. Our findings support the use of ITD to assess other aspects of communities such as the response of trophic groups to the freshness of organic matter, while the MI seems less effective for assessing the ecological status of Rocha Lagoon. Understanding nematode biodiversity and functional traits is crucial for effective ecological quality assessments.

Abstract 4117085: Frequency and Patterns of Paroxysmal Supraventricular Tachycardia Episodes Among Patients Opting For Acute Drug Treatment: Analysis of the NODE-303 Open-Label Etripamil Trial

Background: Etripamil nasal spray (NS) is a fast acting, self-administered calcium channel blocker in development for the termination of AV-nodal-dependent supraventricular tachycardia (SVT). Prior randomized, placebo-controlled and open-label studies have demonstrated favorable safety and efficacy of etripamil in converting paroxysmal supraventricular tachycardia (PSVT) to sinus rhythm (SR) self-administered without direct medical supervision. Research Question/Hypothesis: To assess patterns and annualized PSVT episode frequency among patients opting to self-administer acute treatment with etripamil. Methods: NODE-303 was an event-driven, multi-center, open-label Phase 3 study, conducted in North and South America to evaluate the safety and efficacy of etripamil in patients with documented PSVT over multiple episodes. Test dosing was not performed prior to at-home use. Enrolled patients, upon perceiving symptoms of PSVT: applied an ambulatory ECG monitor, performed a previously trained vagal maneuver and, if symptoms persisted, self-administered etripamil NS 70 mg. During the study, the protocol was amended to allow a repeat dose (70 mg) if symptoms persisted 10 min after the first dose. Each patient could self-treat up to 4 episodes. Results: Of 1,116 enrolled patients, 503 (45.1%) treated ≥1 perceived PSVT episode (safety population). Etripamil achieved conversion to SR in 60% of patients by 30 minutes and 70% by 60 minutes. A total of 220, 118, 62, and 103 patients completed the study with 1, 2, 3, and 4 etripamil-treated perceived episodes of PSVT, respectively, with an average time on study of 440 days. Among these patients, the average number of annualized etripamil-treated PSVT episodes was 3.2 (standard deviation 3.8). Annualized use: etripamil was self-administered for 0-2 PSVT episodes per year, 2-6 episodes, 6-12 episodes, and >12 episodes, in 54%, 32%, 10%, and 4% of patients, respectively (Figure). Conclusions: This analysis aimed to assess the annualized use of etripamil NS in a real-world setting, by analyzing how often patients would self-administer the drug for PSVT episodes. Of patients that self-administered etripamil (n=503), the majority treated >1 episode and the annualized frequency of episodes treated with etripamil was 3.2 episodes/yr.

Trends of Climate Extremes and Their Relationships with Tropical Ocean Temperatures in South America

South America has experienced significant changes in climate patterns over recent decades, particularly in terms of precipitation and temperature extremes. This study analyzes trends in climate extremes from 1979 to 2020 across South America, focusing on their relationships with sea surface temperature (SST) anomalies in the Pacific and Atlantic Oceans. The analysis uses precipitation and temperature indices, such as the number of heavy rainfall days (R10mm, R20mm, R30mm), total annual precipitation (PRCPTOT), hottest day (TXx), and heatwave duration (WSDI), to assess changes over time. The results show a widespread decline in total annual precipitation across the continent, although some regions, particularly in the northeast and southeast, experienced an increase in the intensity and frequency of extreme precipitation events. Extreme temperatures have also risen consistently across South America, with an increase in both the frequency and duration of heat extremes, indicating an ongoing warming trend. The study also highlights the significant role of SST anomalies in both the Pacific and Atlantic Oceans in driving these climate extremes. Strong correlations were found between Pacific SST anomalies (Niño 3.4 region) and extreme precipitation events in the northern and southern regions of South America. Similarly, Atlantic SST anomalies, especially in the Northern Atlantic (TNA), exhibited notable impacts on temperature extremes, particularly heatwaves. These findings underscore the complex interactions between SST anomalies and climate variability in South America, providing crucial insights into the dynamics of climate extremes in the region. Understanding these relationships is essential for developing effective adaptation and mitigation strategies in response to the increasing frequency and intensity of climate extremes.

Epidemiological data of an influenza A/H5N1 outbreak in elephant seals in Argentina indicates mammal-to-mammal transmission.

H5N1 high pathogenicity avian influenza virus has killed thousands of marine mammals in South America since 2022. Here we report epidemiological data and full genome characterization of clade 2.3.4.4b H5N1 HPAI viruses associated with a massive outbreak in southern elephant seals (Mirounga leonina) at Península Valdés, Argentina, in October 2023. We also report on H5N1 viruses in concurrently dead terns. Our genomic analysis shows that viruses from pinnipeds and terns in Argentina form a distinct clade with marine mammal viruses from Peru, Chile, Brazil and Uruguay. Additionally, these marine mammal clade viruses share an identical set of mammalian adaptation mutations which were also present in tern viruses. Our combined ecological and phylogenetic data support mammal-to-mammal transmission and occasional mammal-to-bird spillover and suggest multinational transmission of H5N1 viruses in mammals. We reflect that H5N1 viruses becoming more evolutionary flexible and adapting to mammals in new ways could have global consequences for wildlife, humans, and/or livestock.

The macroeconomic determinants of trade openness in Latin American countries: A panel data analysis

Background Trade openness shows a positive impact on economic growth, supported by economic theory, and export diversification and economic complexity show a positive dynamic in trade openness in the world; however, a specificity is generated in South American countries. Therefore, the objective of the research is to analyse the macroeconomic determinants of trade openness in Latin American countries. Methods The research approach was quantitative and explanatory using panel data methodology from the databases of the World Bank, Harvard University and the Economic Commission for Latin America and the Caribbean for the period 2000-2020. Results The fixed effects panel data model showed that the variables that had a negative impact on trade openness were GDP, the economic complexity index and the logistic performance index, while the variables that had a positive impact were exports of high-tech products (a proxy for innovation), exports, imports, research and development expenditure and interregional trade in goods. Conclusions Therefore, during the analysis period of 2000-2020 in South America, based on the panel data analysis under fixed effects, a total of 8 countries had a negative impact on trade openness, and only the economies of Chile, French Guiana, and Brazil had a positive impact on trade openness; these economies are characterized by their better performance in the economic complexity index, their higher percentage of budget for research and development expenses, and their trade policies oriented towards the industrialization of their value-added products.

Effects of fasting on the interplay between temperature and Trypanosoma cruzi infection on the life cycle of the Chagas disease vector Rhodnius prolixus.

Rhodnius prolixus, a triatomine insect, is one of the most important vectors of Chagas disease in South America. Its interaction with the parasite Trypanosoma cruzi, the causative agent of this disease, is known to be deeply affected by ambient temperature and the nutritional status of the insect vector. In this study, we investigated how starvation affects the life cycle of R. prolixus and the population dynamics of the parasite inside the intestine of the vector at four temperatures ranging from 24°C to 30°C. The weights and molting times of chronically infected and uninfected insects were monitored through repeated 30-day fasting periods from first instar to adult stage, assessing their capacity to retain blood meal weight between developmental stages and tracking parasite concentrations in their urine. Our results demonstrate that ambient temperature is a crucial factor affecting the resistance of R. prolixus to starvation, as survival, body weight, and weight retention greatly decreased in high temperature treatments. Furthermore, we showed that temperature significantly influenced whether T. cruzi established an infection in early instars, with few insects developing infections at the lowest and highest temperature treatments. Additionally, we discovered that a fasting period of 30 days induces a steady decrease in parasite populations in the vector over its lifetime. Infection by T. cruzi had no effect on the survival, molting time, and nutritional factors monitored in our protocol. Our results highlight the importance of nutrition as a determining factor for the development of the vector and the parasite, providing valuable insights for elucidating the complex interplay between temperature and nutrition in shaping the epidemiology of Chagas disease in a changing climate.

A global re-analysis of regionally resolved emissions and atmospheric mole fractions of SF6 for the period 2005–2021

Abstract. We determine the global emission distribution of the potent greenhouse gas sulfur hexafluoride (SF6) for the period 2005–2021 using inverse modelling. The inversion is based on 50 d backward simulations with the Lagrangian particle dispersion model (LPDM) FLEXPART and on a comprehensive observation data set of SF6 mole fractions in which we combine continuous with flask measurements sampled at fixed surface locations and observations from aircraft and ship campaigns. We use a global-distribution-based (GDB) approach to determine baseline mole fractions directly from global SF6 mole fraction fields at the termination points of the backward trajectories. We compute these fields by performing an atmospheric SF6 re-analysis, assimilating global SF6 observations into modelled global three-dimensional mole fraction fields. Our inversion results are in excellent agreement with several regional inversion studies in the USA, Europe, and China. We find that (1) annual US SF6 emissions strongly decreased from 1.25 Gg in 2005 to 0.48 Gg in 2021; however, they were on average twice as high as the reported emissions to the United Nations. (2) SF6 emissions from EU countries show an average decreasing trend of −0.006 Gg yr−1 during the period 2005 to 2021, including a substantial drop in 2018. This drop is likely a direct result of the EU's F-gas regulation 517/2014, which bans the use of SF6 for recycling magnesium die-casting alloys as of 2018 and requires leak detection systems for electrical switch gear. (3) Chinese annual emissions grew from 1.28 Gg in 2005 to 5.16 Gg in 2021, with a trend of 0.21 Gg yr−1, which is even higher than the average global total emission trend of 0.20 Gg yr−1. (4) National reports for the USA, Europe, and China all underestimated their SF6 emissions. (5) Our results indicate increasing emissions in poorly monitored areas (e.g. India, Africa, and South America); however, these results are uncertain due to weak observational constraints, highlighting the need for enhanced monitoring in these areas. (6) Global total SF6 emissions are comparable to estimates in previous studies but are sensitive to a priori estimates due to the low network sensitivity in poorly monitored regions. (7) Monthly inversions indicate that SF6 emissions in the Northern Hemisphere were on average higher in summer than in winter throughout the study period.

Recent progress in atmospheric modeling over the Andes – part I: review of atmospheric processes

The Andes is the longest mountain range in the world, stretching from tropical South America to austral Patagonia (12°N-55°S). Along with the climate differences associated with latitude, the Andean region also features contrasting slopes and elevations, reaching altitudes of more than 4,000 m. a.s.l., in a relatively narrow crosswise section, and hosts diverse ecosystems and human settlements. This complex landscape poses a great challenge to weather and climate simulations. The interaction of the topography with the large-scale atmospheric motions controls meteorological phenomena at scales of a few kilometers, often inadequately represented in global (grid spacing ∼200–50 km) and regional (∼50–25 km) climate simulations previously studied for the Andes. These simulations typically exhibit large biases in precipitation, wind and near-surface temperature over the Andes, and they are not suited to represent strong gradients associated with the regional processes. In recent years (∼2010–2024), a number of modeling studies, including convection permitting simulations, have contributed to our understanding of the characteristics and distribution of a variety of systems and processes along the Andes, including orographic precipitation, precipitation hotspots, mountain circulations, gravity waves, among others. This is Part I of a two-part review about atmospheric modeling over the Andes. In Part I we review the current strengths and limitations of numerical modeling in simulating key atmospheric-orographic processes for the weather and climate of the Andean region, including low-level jets, downslope winds, gravity waves, and orographic precipitation, among others. In Part II, we review how climate models simulate surface-atmosphere interactions and hydroclimate processes in the Andes Cordillera to offer information on projections for land-cover/land-use change or climate change. With a focus on the hydroclimate, we also address some of the main challenges in numerical modeling for the region.

Droughts in Homogeneous Areas of South America and Associated Processes during the Months of Austral Spring and Summer

Droughts in Homogeneous Areas of South America and Associated Processes during the Months of Austral Spring and Summer

Comparison between PCR-RFLP and sequencing techniques in the analysis of Paracoccidioides spp. biodiversity: limitations and insights into species and variant differentiation.

The study of Paracoccidioides spp. faces significant challenges due to limitations inherent in the molecular biology techniques employed. Recently, new species were described whose geographical and genetic distributions were investigated. The phylogenetic studies have revealed that genotypes originally thought to be exclusive in specific regions from South American countries are now being found in other areas of the continent. This finding indicates a broader geographic distribution of these genotypes than previously recognized. To evaluate two molecular biology techniques employed to identify genotypes of Paracoccidioides spp. strains from a Brazilian culture collection previously identified only by mycological methods. DNA samples from 35 Paracoccidioides spp. strains maintained in a Brazilian culture collection were subjected to amplification and enzymatic digestion with PCR-RFLP of tub1 gene, followed by sequencing of gp43 Exon 2 loci. Strains with species identification discrepancies had their tub1 sequences determined to verify possible nucleotide mutations. The genotypic characterization of Paracoccidioides spp. using PCR-RFLP of the tub1 gene identified 22 isolates as P. brasiliensis sensu stricto, two as P. americana, four as P. restrepiensis, and eight as P. lutzii. Sequencing of the gp43 Exon 2 loci revealed discrepancies in the identification of four P. venezuelensis isolates, previously characterized as P. brasiliensis sensu stricto by PCR-RFLP of tub1. The sequencing of tub1 from P. brasiliensis sensu stricto and P. venezuelensis isolates revealed nucleotide differences in the pyrimidine class (C and T) in their sequences, specifically at the position 176bp. These molecular tools were able to establish the genetic diversity within the Paracoccidioides genus, crucial for taxonomy and epidemiology studies. The finding of presence of P. venezuelensis in Brazil, previously thought to be exclusive to Venezuela, highlights genetic connections and evolutionary divergences within the genus. While the PCR-RFLP of tub1technique showed limitations in identifying P. venezuelensis, sequencing of the gp43 Exon 2 loci was able to accurately identify this genotype. Thus, our findings contribute to the understanding of the molecular epidemiology of PCM and emphasize the need for precise species characterization in mycological research.

Giants beasts updated: A review of new knowledge about the South American megafauna

ABSTRACTSince the publication of Megafauna: Giant Beasts of Pleistocene South America by Fariña et al. in 2013, much has been published on this fascinating subject. Here, we sum up those contributions according to their aim: taxonomic, geographical and phylogenetic novelty, new approaches to the natural history of those species, and extinction and its aftermath. The traditional centres of interest since the 19th century, especially the Río de la Plata region, have now been complemented as a source of information by many other regions in South America, and the remains are now being studied by biogeochemistry and molecular biology, as well as with finite element analysis and constantly refined statistics. Finally, scholars and the public are becoming more interested in the demise of the megamammals as the starting point of the current process of biodiversity loss.

Potential role of heterologous flavivirus immunity in preventing urban transmission of yellow fever virus

During the recent yellow fever (YF) epidemics in Brazil, human cases were attributed to spillover infections via sylvatic mosquito transmission. Despite YF virus (YFV) transmission in major urban centers with insufficient vaccination coverage and abundant populations of the domestic vector, Aedes aegypti, there was no evidence of human-amplified transmission. Furthermore, the historic absence of YF in Asia, despite abundant Ae. aegypti and an immunologically naive human population, is unexplained. We tested the hypothesis that pre-existing, heterologous flavivirus immunity, specifically from dengue (DENV) and Zika (ZIKV) viruses, limits YFV viremia and transmission by Ae. aegypti. We infected cynomolgus macaques with DENV or ZIKV, then challenged them 6–9 months later with YFV. We then measured viremia and disease and allowed Ae. aegypti mosquitoes to feed during peak macaque viremia. Although prior heterologous immunity had variable effects on disease, DENV and ZIKV immunity consistently suppressed YFV viremia. Despite no statistical difference due to a small sample size, the suppression in viremia led to a significant reduction in Ae. aegypti infection and a lack of transmission potential. These results support the hypothesis that, in DENV- and ZIKV-endemic regions such as South America and Asia, human flavivirus immunity suppresses YFV human amplification potential, reducing the risk of urban outbreaks.

VLIK from Madrid to Vienna: the Search for a New Political Direction in the Liberation of Lithuania

The Supreme Committee for the Liberation of Lithuania (Vyriausiasis Lietuvos išlaisvinimo komitetas, VLIK), relying on its right to speak on behalf of the subjugated nation and its belief in the meaning of the Helsinki Accords, emphasised the importance of the Madrid conference for the liberation activities of Lithuania. One more aspect of the Final Act of the Conference on Security and Cooperation in Europe, specifically the territorial integrity principle applicable to the liberation process of the Baltic States, was raised in the Spanish capital. Starting in 1981, the VLIK sought to draw international attention to the situation of Lithuanian dissidents in the Soviet Union and drafted memoranda on the situation in Lithuania. After it was ascertained that there was no possibility to raise the case of Lithuania’s freedom at the United Nations, focus was shifted to the situation evolving in Europe. A permanent VLIK representative for maintaining contacts with the European Parliament (EP) was therefore appointed. In co-operation with the Lithuanian diplomatic service and political organisations, the VLIK operated consistently and saw the passing of an EP resolution on the situation in the Baltic States in 1983. Observing signs of a new political trend in the liberation process of Lithuania, the VLIK sought to ensure that the ‘passive position of non-recognition of the occupation of Lithuania’ would become ‘an active and effective campaign’. To this end, expanding the geographical scope of its political activities, the VLIK established and strengthened its representative offices in North and South America, Australia, and Europe. The earlier strategy of cooperation between Lithuanians in the free world and those in the occupied country remained. Having established its intention to restore the ‘execution of the sovereign powers of Lithuania’, VLIK urged political figures at the Vienna conference to hold ‘a broader campaign in Europe’.

Population density estimates and conservation status of Aegla jacutinga Marçal & Teixeira, 2020 (Decapoda: Anomura: Aeglidae) from the type locality in Brazil

Abstract Anomuran crabs of the genus AeglaLeach, 1821 are endemic to temperate and subtropical regions of South America and are commonly found in streams and rivers, where they are generally restricted to healthy environments because they are sensitive to environmental changes. The genus presents worrying data regarding its conservation, like the many Brazilian freshwater species classified as being at some level of threat of extinction. We inventoried unexplored watersheds, estimated the population density of Aegla jacutinga Marçal & Teixeira, 2020 in its type locality, updated information on the distribution of the species, and assessed its conservation status using IUCN criteria.

Wood hardness drives nest-site selection in woodpeckers of the humid Chaco

Abstract Avian excavators (woodpeckers and other species) select nest sites based on characteristics of the nest patch, nest tree, and substrate. These characteristics could increase foraging opportunities or reduce the risk of predation, but there is also a potentially important role for wood hardness in restricting nest-site selection, a role that has been little explored and is expected to vary among species according to their ability to excavate. We examined patterns of nest-site selection in 8 woodpecker species in the humid Chaco of South America, where the dominant trees have extremely hard wood. We hypothesized that (1) wood hardness is the main factor driving selection of excavation sites, and (2) interspecific variation in body size and foraging behavior (traits frequently related to excavation ability) explain interspecific variation in the wood hardness of excavated nest substrates. From 2016 to 2019 in well-preserved forests of the Argentine Chaco, we compared nesting cavities excavated in wood (cases; n = 42) vs. potential wood substrates without cavities (matched controls) and made 187 focal observations of foraging woodpeckers. Woodpeckers selected nesting substrates with softer heartwood than potential substrates, regardless of any other characteristics of the tree or nest patch. Wood hardness around nest cavities increased with body size and the prevalence of chiseling during foraging, traits that were positively correlated. Woodpeckers often excavated in Prosopis spp. (Algarrobos) but rarely in Schinopsis balansae (Quebracho), a tree with exceptionally hard internal wood, in which cavity adopters frequently nest in non-excavated cavities. Wood hardness is critical to assessing the role of woodpeckers as cavity facilitators, understanding the costs and benefits of excavation, and interpreting excavation patterns across species and forests globally.