Landsat sub-pixel land cover dynamics in the Brazilian Amazon

The Brazilian Amazon land cover changes rapidly due to anthropogenic and climate drivers. Deforestation and forest disturbances associated with logging and fires, combined with extreme droughts, warmer air, and surface temperatures, have led to high tree mortality and harmful net carbon emissions in this region. Regional attempts to characterize land cover dynamics in this region focused on one or two anthropogenic drivers (i.e., deforestation and forest degradation). Land cover studies have also used a limited temporal scale (i.e., 10–15 years), focusing mainly on global and country-scale forest change. In this study, we propose a novel approach to characterize and measure land cover dynamics in the Amazon biome. First, we defined 10 fundamental land cover classes: forest, flooded forest, shrubland, natural grassland, pastureland, cropland, outcrop, bare and impervious, wetland, and water. Second, we mapped the land cover based on the compositional abundance of Landsat sub-pixel information that makes up these land cover classes: green vegetation (GV), non-photosynthetic vegetation, soil, and shade. Third, we processed all Landsat scenes with <50% cloud cover. Then, we applied a step-wise random forest machine learning algorithm and empirical decision rules to classify intra-annual and annual land cover classes between 1985 and 2022. Finally, we estimated the yearly land cover changes in forested and non-forested ecosystems and characterized the major change drivers. In 2022, forest covered 78.6% (331.9 Mha) of the Amazon biome, with 1.4% of secondary regrowth in more than 5 years. Total herbaceous covered 15.6% of the area, with the majority of pastureland (13.5%) and the remaining natural grassland. Water was the third largest land cover class with 2.4%, followed by cropland (1.2%) and shrubland (0.4%), with 89% overall accuracy. Most of the forest changes were driven by pasture and cropland conversion, and there are signs that climate change is the primary driver of the loss of aquatic ecosystems. Existing carbon emission models disregard the types of land cover changes presented in the studies. The twenty first century requires a more encompassing and integrated approach to monitoring anthropogenic and climate changes in the Amazon biome for better mitigation, adaptation, and conservation policies

Effect of the extract of Ricinus communis L. on the osmotic fragility, labeling of red blood cells with Technetium-99m and morphology of the cells

The aim of this study was to evaluate the influence of the proteic extract of R. communis on the cell physiology by the osmotic fragility, labeling of the blood elements with the 99mTc and cell morphology. To evaluate the osmotic fragility, the blood samples of the Wistar rats were incubated with the concentrations of R. communis and with the solutions of NaCl (0.4; 0.7; 0.9%). In the labeling of the blood elements procedure, the rat blood was treated with a solution of Tc-99m and TCA at 5%, determining the rate of radioactivity (%ATI) in the plasma (P) and in the red blood cells (RBC). The soluble and insoluble fractions of the plasma were also evaluated. The cells morphology submitted to the extract was evaluated by the optical microscopy (x40). The results indicated that the rate of the hemolysis increased in the presence of 0.125 mg/mL of the extract. There was a decay of 49.69% in the rate of ATI in the insoluble fraction of the cells, with the morphological alterations in the red blood cells. These results suggested that the extract changed the capability of binding of the red blood cells due to the stannous ion oxidation, modifying the cells structure.<br>Produtos naturais são usados freqüentemente por muitas pessoas no tratamento do câncer. O Ricinus communis L é uma Euforbiaceae que apresenta propriedades laxativas, purgativas e antitumorais. O objetivo deste trabalho é estudar a influência da fração protéica do extrato hidroalcoólico de R. communis L. na fisiologia celular através da fragilidade osmótica, da marcação de elementos sanguíneo com 99mTc e da morfologia celular. Para avaliar a fragilidade osmótica, amostras de sangue de ratos Wistar foram incubadas com concentrações de R. communis e com soluções de NaCl (0,4; 0,7; 0,9%). No procedimento de marcação de elementos sanguíneos, as amostras de sangue foram tratadas com solução de Tc-99m e TCA à 5%, determinando o percentual de radioatividade (%ATI) no plasma (P) e nas células vermelhas (RBC); as frações solúvel e insolúvel do plasma também foram avaliadas. A morfologia das células submetidas ao extrato foi avaliada por microscopia óptica (x40). Os resultados indicam que o extrato na concentração de 0,125 mg/mL provoca hemólise de 49,69% , no % ATI na fração insolúvel das células, ocorrendo alterações morfológicas das células sangüíneas. Esses resultados sugerem que o extrato radiomodifica a ligação do 99mTc às células vermelhas. Isto pode ser devido à oxidação do íon estanoso, a um processo de competição com os sítios de ligação do 99mTc ou por modificação das estruturas da membrana

Níveis de nitrogênio e a taxa fotossintética do mamoeiro "golden" Nitrogen levels and photosynthetic rate of papaya 'golden'

Objetivou-se neste trabalho, avaliar o efeito da nutrição nitrogenada sobre alguns aspectos relacionados à taxa fotossintética em plantas de mamão da variedade "Golden". As plantas foram cultivadas em vasos sob condições de casa de vegetação, em soluções nutritivas contendo três concentrações de N-N3- (1,0; 5,0 e 8,0molm-3). O delineamento experimental foi em blocos casualizados, com sete repetições. As avaliações foram realizadas 61 dias após o início do experimento. Observou-se que a deficiência de nitrogênio reduziu a matéria seca total; no entanto, a relação raiz:parte aérea foi maior nessas plantas. A taxa fotossintética líquida foi reduzida pela menor disponibilidade de nitrogênio. Os resultados observados para a condutância estomática e a correlação negativa encontrada entre a taxa fotossintética e a concentração interna de CO2 claramente indicam que a menor taxa fotossintética não foi devida à limitação estomática. Adicionalmente, a redução verificada nas concentrações de pigmentos foliares, como as clorofilas a e b e os carotenóides, também pode ter contribuído para a menor taxa fotossintética e o menor crescimento das plantas. A taxa transpiratória foi maior para as plantas cultivadas sob estresse; como conseqüência, observou-se, para essas plantas, menor ganho de CO2 por unidade de água transpirada.<br>This research was aimed at evaluating the effect of nitrogen (N) levels on some aspects related to the photosynthetic rate in plants of papaya Cv. Golden. The plants were cultivated under greenhouse conditions on different nutritional solutions with three concentrations of N-N3- (1.0; 5.0; 8.0molm-3). The experiment was carried out under a randomized blocks experimental design, with seven repetitions. The evaluations occurred on the 61st day after the beginning of the experiment. The nitrogen deficiency reduced the total dry mass; however, the relation root:shoot was highest for these plants. The photosynthetic rate was reduced by the lesser nitrogen availability. The results observed for the stomatal conductance and the negative correlation found between the photosynthesis and the internal concentration of CO2, indicate clearly that the reduced photosynthetic rate was not due to stomatal limitation. Additionally, the reduction verified in leaf pigments, such as chlorophylls a and b and carotenoids also could have been contributed for the reduction on photosynthesis rate and growth of these plants. Transpiratory rate was higher for the plants cultivated under stress; as consequence it was observed, for these plants, minor CO2 profit for unit of transpirated water