Abstract The Value Added Tax (VAT) represents the first source of tax revenue for the Ecuadorian economy due to its broad tax base and ease of collection, characteristics that allow this tax to generate a large amount of revenue necessary to increase the quality and quantity of public services in Ecuador. The objective of this paper is to identify the incidence of economic growth and the tax pressure on VAT collection for the period 2000-2019. An Ordinary Least Squares (OLS) model transformed by the Box-Cox methodology was used in conjunction with the Prais-Winsten and Cochrane-Orcutt procedure. The results show the existence of a positive relationship between economic growth and VAT revenue, as well as a positive relationship between tax pressure and VAT revenue. However, when considering the squared tax pressure variable, it became evident that, if the tax pressure increases above the optimal point, the results on VAT revenue will be negative. The results are found to be in line with other papers measuring these variables.

Resumen El Impuesto al Valor Agregado (IVA) representa la primera fuente de ingresos tributarios para la economía ecuatoriana debido a la amplia base tributaria y facilidad de cobro que posee, características que permiten a este tributo generar una gran masa de ingresos, necesarios para aumentar la calidad y cantidad de servicios públicos en el Ecuador. El objetivo de este trabajo es identificar la incidencia del crecimiento económico y la presión fiscal en la recaudación del IVA para el periodo 2000-2019. Se utilizó un modelo de Mínimos Cuadrados Ordinarios (MCO) transformado mediante la metodología de Box-Cox conjuntamente con el procedimiento Prais-Winsten y Cochrane-Orcutt. Los resultados exponen la existencia de una relación positiva entre el crecimiento económico y la recaudación del IVA, y así mismo una relación positiva entre la presión fiscal y la recaudación del IVA, sin embargo, al considerar la variable presión fiscal elevada al cuadrado dejó evidencia que, si la presión fiscal se incrementa por encima del punto óptimo, los resultados en la recaudación del IVA serán negativos. Se encuentra que los resultados guardan relación con otros trabajos que miden estas variables.

African animal trypanosomiasis causes significant economic losses in sub-Saharan African countries because of livestock mortalities and reduced productivity. Trypanosomes, the causative agents, are transmitted by tsetse flies (Glossina spp.). In the current study, we compared and contrasted the virulence characteristics of five Trypanosoma congolense and Trypanosoma brucei isolates using groups of Swiss white mice (n = 6). We further determined the vectorial capacity of Glossina pallidipes, for each of the trypanosome isolates. Results showed that the overall pre-patent (PP) periods were 8.4 ± 0.9 (range, 4-11) and 4.5 ± 0.2 (range, 4-6) for T. congolense and T. brucei isolates, respectively (p < 0.01). Despite the longer mean PP, T. congolense-infected mice exhibited a significantly (p < 0.05) shorter survival time than T. brucei-infected mice, indicating greater virulence. Differences were also noted among the individual isolates with T. congolense KETRI 2909 causing the most acute infection of the entire group with a mean ± standard error survival time of 9 ± 2.1 days. Survival time of infected tsetse flies and the proportion with mature infections at 30 days post-exposure to the infective blood meals varied among isolates, with subacute infection-causing T. congolense EATRO 1829 and chronic infection-causing T. brucei EATRO 2267 isolates showing the highest mature infection rates of 38.5% and 23.1%, respectively. Therefore, our study provides further evidence of occurrence of differences in virulence and transmissibility of eastern African trypanosome strains and has identified two, T. congolense EATRO 1829 and T. brucei EATRO 2267, as suitable for tsetse infectivity and transmissibility experiments.

Durante o experimento "O Impacto da Seca Prolongada nos Fluxos de Água e Dióxido de Carbono em uma Floresta Tropical Amazônica" (ESECAFLOR) realizou-se este trabalho. Trata-se de um subprojeto do Experimento de Grande escala da Biosfera-Atmosfera da Amazônia (LBA), localizado na Estação Científica Ferreira Pena, dentro da Floresta Nacional de Caxiuanã, Pará (1º 42- 30-- S; 51º 31-45-- W; 62 m altitude). A região tem floresta bem preservada, com dossel médio de 35 m. As espécies predominantes em terra-firme, são: Eschweilera coriacea (Mata-matá branco), Voucapoua americana (Acapu) e Protium pallidum (Breu Branco). Medidas foram realizadas entre 03 a 16 de dezembro de 2000 e 12 a 25 de janeiro de 2003, objetivando-se determinar a transpiração de dois exemplares de Eschweilera coriacea, mediante os efeitos da seca provocada. A área do ESECAFLOR compreende duas parcelas, cada uma com 1 ha, parcela A (controle) e parcela B (exclusão da chuva). Para o fluxo de seiva, o método foi o Balanço de Calor no Tronco, com sistema Sap Flow meter, P4.1; entre os períodos analisados, a transpiração média registrou aumento de 56% na árvore A237 (parcela A) e redução de 68% na árvore B381 (parcela B).

During the "Long-term impact of drought on water and carbon dioxide fluxes in Amazonian Tropical Rainforest Experiment" (ESECAFLOR), this study was carried out, which is a subproject of Large Scale Biosphere Atmosphere Experiment in Amazônia (LBA), located in the Ferreira Penna Scientific Station (FPSS) in the Caxiuanã National Forest (CNF) in Pará State (1º 42- 30-- S; 51º 31-45-- W; 62 m altitude). The region has a well-preserved forest, with canopy of 35 m. The predominate tree species in the landscape are Eschweilera coriacea (White Matá-matá), Voucapoua americana (Acapu) and Protium pallidum (White Pitch). Sap flow measurements were made in the wet season (03-16 December 2000 and 12-25 January 2003), to evidence the effect of long term induced drought, aiming to determinate the transpiration of Eschweilera coriacea. The ESECAFLOR site consists of two different areas with 1 ha each. Plot A (control) and Plot B (rainfall exclusion). The Trunk Heat Balance (THB) method was applied to sap flow measurements, by Sap Flow Meter P4.1 system. Between analysed periods, the mean transpiration of E. Coriacea increased 56% in the tree A237 (control plot) and decreased 68% in B381 (drought plot).