Feedback in tropical forests of the Anthropocene

Tropical forests are complex systems containing myriad interactions and feedbacks with their biotic and abiotic environments, but as the world changes fast, the future of these ecosystems becomes increasingly uncertain. In particular, global stressors may unbalance the feedbacks that stabilize tropical forests, allowing other feedbacks to propel undesired changes in the whole ecosystem. Here, we review the scientific literature across various fields, compiling known interactions of tropical forests with their environment, including the global climate, rainfall, aerosols, fire, soils, fauna, and human activities. We identify 170 individual interactions among 32 elements that we present as a global tropical forest network, including countless feedback loops that may emerge from different combinations of interactions. We illustrate our findings with three cases involving urgent sustainability issues: (1) wildfires in wetlands of South America; (2) forest encroachment in African savanna landscapes; and (3) synergistic threats to the peatland forests of Borneo. Our findings reveal an unexplored world of feedbacks that shape the dynamics of tropical forests. The interactions and feedbacks identified here can guide future qualitative and quantitative research on the complexities of tropical forests, allowing societies to manage the nonlinear responses of these ecosystems in the Anthropocene

Feedback between drought and deforestation in the Amazon

Deforestation and drought are among the greatest environmental pressures on the Amazon rainforest, possibly destabilizing the forest-climate system. Deforestation in the Amazon reduces rainfall regionally, while this deforestation itself has been reported to be facilitated by droughts. Here we quantify the interactions between drought and deforestation spatially across the Amazon during the early 21st century. First, we relate observed fluctuations in deforestation rates to dry-season intensity; second, we determine the effect of conversion of forest to cropland on evapotranspiration; and third, we simulate the subsequent downwind reductions in rainfall due to decreased atmospheric water input. We find large variability in the response of deforestation to dry-season intensity, with a significant but small average increase in deforestation rates with a more intense dry season: With every mm of water deficit, deforestation tends to increase by 0.13% per year. Deforestation, in turn, has caused an estimated 4% of the recent observed drying, with the south-western part of the Amazon being most strongly affected. Combining both effects, we quantify a reinforcing drought-deforestation feedback that is currently small, but becomes gradually stronger with cumulative deforestation. Our results suggest that global climate change, not deforestation, is the main driver of recent drying in the Amazon. However, a feedback between drought and deforestation implies that increases in either of them will impede efforts to curb both.</p

Controle de bolor azul e verde em frutas de citros armazenadas em câmara fria pelo uso do gás de ozônio

O objetivo deste trabalho foi estudar o efeito do ozônio sobre /Penicillium/ /italicum/ (PI) e /P/. /digitatum/ (PD) de citros. O ensaio foi conduzido em duas câmara-fria, uma com liberação de gás ozônio (0,09 ppm, AgroCare modelo OP 35 da Interozone) e outra sem, a temperatura de 4°C e as cultivares testadas foram Lane Late e Ortanique. Frutos foram inoculados pela imersão em suspensão de 10 4 esporos ml-1 e pela deposição da suspensão na superfície do fruto seguida de ferimento com agulha. No segundo ensaio, a inoculação por ferimento foi feita usando-se um furador de rolha, previamente imerso em suspensão de 106 esporos ml-1. O experimento foi inteiramente casualizado com quatro repetições, cinco e dez frutos por parcela, respectivamente, no primeiro e segundo ensaio. A avaliação foi feita pela medição do diâmetro da lesão e índice de esporulação do fungo (IEF). No primeiro e segundo ensaio, os sintomas da doença começaram a surgir, respectivamente, 28 dias e 14 dias após a inoculação por ferimento, enquanto por imersão só depois de 56 dias. O uso do ozônio não reduziu o diâmetro da lesão provocado pelo fungo. Entretanto, o ozônio inibiu a esporulação de PD e PI em frutos, pois o IEF foi muito baixo, apesar de não inibir o crescimento micelial, mostrando que seu uso é promissor

Lower IgG somatic hypermutation rates during acute dengue virus infection is compatible with a germinal center-independent B cell response

Reads, clonal groups, and lineages numbers per individual and condition. The table shows the number of raw and used sequences as well as the number of clonotypes and lineages per individual. (XLS 30 kb

Impact of the Salud Mesoamerica Initiative on delivery care choices in Guatemala, Honduras, and Nicaragua

Background The Salud Mesoamérica Initiative (SMI) is a public-private collaboration aimed to improve maternal and child health conditions in the poorest populations of Mesoamerica through a results-based aid mechanism. We assess the impact of SMI on the staffing and availability of equipment and supplies for delivery care, the proportion of institutional deliveries, and the proportion of women who choose a facility other than the one closest to their locality of residence for delivery. Methods We used a quasi-experimental design, including baseline and follow-up measurements between 2013 and 2018 in intervention and comparison areas of Guatemala, Nicaragua, and Honduras. We collected information on 8754 births linked to the health facility closest to the mother’s locality of residence and the facility where the delivery took place (if attended in a health facility). We fit difference-in-difference models, adjusting for women’s characteristics (age, parity, education), household characteristics, exposure to health promotion interventions, health facility level, and country. Results Equipment, inputs, and staffing of facilities improved after the Initiative in both intervention and comparison areas. After adjustment for covariates, institutional delivery increased between baseline and follow-up by 3.1 percentage points (β = 0.031, 95% CI -0.03, 0.09) more in intervention areas than in comparison areas. The proportion of women in intervention areas who chose a facility other than their closest one to attend the delivery decreased between baseline and follow-up by 13 percentage points (β = − 0.130, 95% CI -0.23, − 0.03) more than in the comparison group. Conclusions Results indicate that women in intervention areas of SMI are more likely to go to their closest facility to attend delivery after the Initiative has improved facilities’ capacity, suggesting that results-based aid initiatives targeting poor populations, like SMI, can increase the use of facilities closest to the place of residence for delivery care services. This should be considered in the design of interventions after the COVID-19 pandemic may have changed health and social conditions.Peer Reviewe

Hospitalização por pneumonia: influência de fatores socioeconômicos e gestacionais em uma coorte de crianças no Sul do Brasil

OBJETIVO: Investigar a influência de fatores socioeconômicos e gestacionais sobre a hospitalização por pneumonia no período pós-neonatal. MATERIAL E MÉTODO: Longitudinal. Crianças com idade entre 28 e 364 dias, nascidas na cidade de Pelotas, RS (Brasil), em 1993. A definição de caso foi a permanência em ambiente hospitalar por um período igual ou superior a 24 horas em conseqüência de pneumonia. Foi aplicado delineamento longitudinal. RESULTADOS: Dentre as 5.304 crianças da coorte, 152 (2,9%) foram hospitalizadas por pneumonia no período. O valor preditivo positivo do diagnóstico clínico comparado com o radiológico alcançou 76%. A análise através de regressão logística mostrou que a classe social e a escolaridade materna estiveram forte e inversamente associadas à admissão hospitalar. Filhos de mães adolescentes tiveram risco duplicado à internação; paridade igual ou superior a três representou risco 2,8 vezes maior em relação às mães primíparas; ganho de peso inferior a 10 kg durante a gestação implicou risco cerca de 40% maior à hospitalização. CONCLUSÕES: A classe social e a escolaridade materna foram os principais determinantes da hospitalização. Idade e paridade materna e o ganho de peso durante a gestação foram também fatores de risco importantes.OBJECTIVE: To investigate the influence of socioeconomic and gestational factors on admission due to pneumonia in the post-neonatal period. METHODOLOGY: Cohort. Children born in the city Pelotas, Brazil, in 1993. Cases were children admitted to hospital for 24 hours or more, between the ages of 28 and 364 days, with a diagnosis of pneumonia. RESULTS: Of the 5,304 children in the cohort, 152 (2.9%) were hospitalized with pneumonia. The positive preditive value of the clinical diagnosis compared to the radiological assessment was 76%. Analysis by conditional logistic regression showed that social class and maternal schooling were strongly inversely associated with pneumonia. Children of adolescent mothers were twice as likely to be admitted. The relative risk for children whose mothers were of parity three or greater was 2.8 relative to primiparae. Maternal weight gain during pregnancy of less than 10 kg was associated with a 40% increase in risk. CONCLUSION: Socioeconomic factors were important determinants of pneumonia admissions. Maternal age, parity and weight gain were also significant risk factors

Prevalence of anemia and deficiency of iron, folic acid, and zinc in children younger than 2 years of age who use the health services provided by the Mexican Social Security Institute

<p>Abstract</p> <p>Background</p> <p>In Mexico, as in other developing countries, micronutrient deficiencies are common in infants between 6 and 24 months of age and are an important public health problem. The objective of this study was to determine the prevalence of anemia and of iron, folic acid, and zinc deficiencies in Mexican children under 2 years of age who use the health care services provided by the Mexican Institute for Social Security (IMSS).</p> <p>Methods</p> <p>A nationwide survey was conducted with a representative sample of children younger than 2 years of age, beneficiaries, and users of health care services provided by IMSS through its regular regimen (located in urban populations) and its Oportunidades program (services offered in rural areas). A subsample of 4,955 clinically healthy children was studied to determine their micronutrient status. A venous blood sample was drawn to determine hemoglobin, serum ferritin, percent of transferrin saturation, zinc, and folic acid. Descriptive statistics include point estimates and 95% confidence intervals for the sample and projections for the larger population from which the sample was drawn.</p> <p>Results</p> <p>Twenty percent of children younger than 2 years of age had anemia, and 27.8% (rural) to 32.6% (urban) had iron deficiency; more than 50% of anemia was not associated with low ferritin concentrations. Iron stores were more depleted as age increased. Low serum zinc and folic acid deficiencies were 28% and 10%, respectively, in the urban areas, and 13% and 8%, respectively, in rural areas. The prevalence of simultaneous iron and zinc deficiencies was 9.2% and 2.7% in urban and rural areas. Children with anemia have higher percentages of folic acid deficiency than children with normal iron status.</p> <p>Conclusion</p> <p>Iron and zinc deficiencies constitute the principal micronutrient deficiencies in Mexican children younger than 2 years old who use the health care services provided by IMSS. Anemia not associated with low ferritin values was more prevalent than iron-deficiency anemia. The presence of micronutrient deficiencies at this early age calls for effective preventive public nutrition programs to address them.</p

The progressive elevation of alpha fetoprotein for the diagnosis of hepatocellular carcinoma in patients with liver cirrhosis

BACKGROUND: Hepatocellular carcinoma is the most common cause of primary liver neoplasms and is one of the main causes of death in patients with liver cirrhosis. High Alpha fetoprotein serum levels have been found in 60–70% of patients with Hepatocellular carcinoma; nevertheless, there are other causes that increase this protein. Alpha fetoprotein levels ≥200 and 400 ng/mL in patients with an identifiable liver mass by imaging techniques are diagnostic of hepatocellular carcinoma with high specificity. METHODS: We analysed the sensitivity and specificity of the progressive increase of the levels of alpha fetoprotein for the detection of hepatocellular carcinoma in patients with liver cirrhosis. Seventy-four patients with cirrhosis without hepatocellular carcinoma and 193 with hepatic lesions diagnosed by biopsy and shown by image scans were included. Sensitivity and specificity of transversal determination of alpha fetoprotein ≥ 200 and 400 ng/mL and monthly progressive elevation of alpha fetoprotein were analysed. Areas under the ROC curves were compared. Positive and negative predictive values adjusted to a 5 and 10% prevalence were calculated. RESULTS: For an elevation of alpha fetoprotein ≥ 200 and 400 ng/mL the specificity is of 100% in both cases, with a sensitivity of 36.3 and 20.2%, respectively. For an alpha fetoprotein elevation rate ≥7 ng/mL/month, sensitivity was of 71.4% and specificity of 100%. The area under the ROC curve of the progressive elevation was significantly greater than that of the transversal determination of alpha fetoprotein. The positive and negative predictive values modified to a 10% prevalence are of: 98.8% and 96.92%, respectively; while for a prevalence of 5% they were of 97.4% and 98.52%, respectively. CONCLUSION: The progressive elevation of alpha fetoprotein ≥7 ng/mL/month in patients with liver cirrhosis is useful for the diagnosis of hepatocellular carcinoma in patients that do not reach αFP levels ≥200 ng/mL. Prospective studies are required to confirm this observation