Universidade Federal Rural da Amazônia

Productivity, litter dynamics and soil fertility in agroforestry systems with coconut and cupuassu trees in eastern amazon

Abstract Agroforestry systems (AFS) are sustainable land use strategies that promote productivity and environmental conservation. The intercropping of coconut palm ( Cocos nucifera L.) and five progenies of cupuassu trees [ Theobroma grandiflorum (Willd. ex Spreng.) Schum.] was e...

Measuring Backdoor Persistence in Post-trained Large Language Models: The Cyber Resilience Scaling Coefficient

Data-poisoning backdoors implanted during supervised fine-tuning of large language models persist through subsequent clean training, yet the field lacks a bounded, scale-normalized metric for quantifying and comparing this persistence across architectures and training regimes. We...

Bertholletia excelsa Shell–Based Wood–Plastic with Upcycled Polypropylene: An Amazonian Feedstock for Circular Bioeconomy Applications

Environmental accumulation issues arise from discarded waste, synthetic, and natural polymers in landfills, whose slow degradation exacerbates the problem. These materials can be upcycled as renewable feedstocks and properly reused. Therefore, this research examines the fabricati...

Informality, power and governance in the global value chain of Brazil nuts in Brazil and Bolivia

Purpose How does governance in global value chains (GVC) work when their main coordination and control mechanisms rely on power asymmetries rather than formal institutions? This study aims to examine a case study set in a context typical of informality and institutional fragility...

Variation in apparent wood density of Tachigali vulgaris as affected by tree diameter, height, forking, and soil conditions in Amazonian plantations

Abstract Tachigali vulgaris has potential for energy purposes in the Amazon, but the relationship between several silvicultural factors and wood quality requires further investigation. This study evaluated the variation in the apparent density of T. vulgaris wood in two pure plan...

Persistent Redox Imbalance in Post-COVID-19 Syndrome: Lipid Peroxidation, Antioxidant Enzyme Depletion, and Reduced Nitric Oxide Availability in an Amazonian Population

Post-COVID-19 syndrome (PCS) can persist even after mild acute illness, and oxidative stress has been proposed as a central mechanism for this persistence, although it remains poorly studied in the Amazon. This study characterized redox imbalance in patients with PCS through a co...