Repositorio Digital Ikiam (Univ. Regional Amazónica)
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Biogas from a full scale digester operated in psychrophilic conditions and fed only with fruit and vegetable waste
Get PDFThe aim of this work was to evaluate the feasibility of treating fruit and vegetable waste from a municipal market in a full-scale anaerobic digester with minimum implementation and operational costs, i.e. without pre-treatment, clean water consumption, active heating or mixing. For this purpose, a 13.9 m3 digester that forces the submersion of solids, gains heat through solar radiation and recirculates effluent was monitored during one year of real operational and weather conditions in Bolivia. The digester was initially loaded with cow rumen (inoculum source), and after eight weeks with only fruit and vegetable waste. The digester operated at an organic loading rate (OLR) of 1 kgVS/(m3d). The normalized specific biogas production averaged 0.26 m3/kgVS and increased to 0.34 m3/kgVS when OLR was halved to 0.57 kgVS/(m3d), while the passive solar design allowed an average digester temperature of 21 °C (4 °C above the average ambient temperature)
Predicting suitable nesting sites for the Blackcaiman (Melanosuchus niger Spix 1825) in theCentral Amazon basin
Get PDFAfter many years of illegal hunting and commercialization, the populations of the Black caiman (Melanosuchus niger) have been recovering during the last four decades due to the enforcement of a legislation that inhibits their international commercialization. Protecting nesting sites, in which vulnerable life forms (as reproductive females, eggs, and neonates) spend considerable time, is one of the most appropriate conservation actions aimed at preserving caiman populations. Thus, identifying priority areas for this activity should be the primary concern of conservationists. As caiman nesting sites are often found across the areas with difficult access, collecting nest information requires extensive and costly fieldwork efforts. In this context, species distribution modeling can be a valuable tool for predicting the locations of caiman nests in the Amazon basin. In this work, the maximum entropy method (MaxEnt) was applied to model the M. niger nest occurrence in the Mamirauá Sustainable Development Reserve (MSDR) using remotely sensed data. By taking into account the M. niger nesting habitat, the following predictor variables were considered: conditional distance to open water, distance to bare soil, expanded contributing area from drainage, flood duration, and vegetation type. The threshold-independent prediction performance and binary prediction based on the threshold value of 0.9 were evaluated by the area under the curve (AUC) and performing a binomial test, respectively. The obtained results (AUC = 0.967 ± 0.006 and a highly significant binomial test P<0.01) indicated excellent performance of the proposed model in predicting the M. niger nesting occurrence in the MSDR. The variables related to hydrological regimes (conditional distance to open water, expanded contributing area from drainage, and flood duration) most strongly affected the model performance. MaxEnt can be used for developing community-based sustainable management programs to provide socio-economic benefits to local communities and promote species conservation in a much larger area within the Amazon basin
Análisis del título de anticuerpos en cerdas vacunadas contra peste porcina clásica a cuatro edades de gestación
Get PDFEn el presente estudio se evaluó la respuesta inmune adquirida por vacunación contra la peste porcina clásica (PPC) en cerdas a cuatro edades distintas de gestación (70, 75, 80 y 90 días) empleando la vacuna Pest-Vac® (Pfizer). Se tomaron muestras de sangre 24 horas previas a la vacunación y 72 horas después del parto. Se determinó el nivel de anticuerpos mediante ELISA de bloqueo. No se encontró diferencia significativa entre los títulos de anticuerpos generados por la vacunación según la edad de gestación ni tampoco entre las muestras prevacunales y del posparto. Sin embargo, el efecto del número de parto, utilizado como covariable, presentó diferencia significativa (p<0.05) en el título de anticuerpos contra PP
La paternidad como medio de realización masculina en Guatemala y Costa Rica
Get PDFHoy en día los estudios de masculinidad son abundantes, al igual que sus
enfoques y acciones sociales; sin embargo, se carece de una propuesta
que facilite el estudio teórico y empírico de la temática. Para resolver estas
dificultades se desarrolló la concepción de masculinidad dominante, en la cual
se propone que los hombres asumen disposiciones socialmente estructuradas
para integrarse funcionalmente a la sociedad; entre las disposiciones
estudiadas destaca la paternidad. En términos objetivos la paternidad
se entiende como una relación biológica y sociojurídica de derechos y
obligaciones que los hombres establecen con sus hijos e hijas; sin embargo,
en el plano subjetivo, la paternidad es un medio de realización masculina que
pasa por tres variables: la procreación, la crianza y el cuidado. A pesar de las
condiciones sociales, culturales y económicas que dificultan la realización de
la paternidad, se encontraron indicios de apego a esta disposición en 1057
hombres jóvenes, en Guatemala y Costa Rica. En este artículo se analizan
estos datos y se ensayan interpretaciones cualitativas de los resultados
Formación de públicos en el cine ecuatoriano
Get PDFEl objetivo de esta investigación es hacer un análisis de como en los últimos once años el cine ecuatoriano ha
intentado afianzarse dentro de un complejo mercado capitalista cinematográfico, con la ayuda de políticas y
proyectos encaminados a fortalecerlo. En este marco, se estudió la iniciativa Territorios de Cine: sus alcances,
limitaciones y acciones destinadas a la formación de públicos. Se concluye como estas acciones no logran llegar a sus objetivos, ya que deben estar acompañadas de un sistema de información e investigación que permita un conocimiento acerca de la gran esfera del quehacer cinematográfico, sus audiencias, políticas y resultados. Si bien esta iniciativa ha permitido que las comunidades puedan acceder gratuitamente a filmes ecuatorianos, al mismo tiempo ha dejado de lado la necesidad de obtener información estadística, teórica y práctica de las audiencias, através de un conocimiento que debe ser registrado
Parasitism of the isopod Riggia puyensis Rodríguez-Haro et al. in two armored catfish from Pastaza Province (Ecuador)
Get PDFRiggia puyensis, an ectoparasitic isopod, was collected in juvenile Chaetostoma breve and Chaetostoma microps host specimens from the Amazonian region of Ecuador. The aim of this work is to study the possible injury that the parasite causes in its host. R. puyensis was found covered by a fold of the skin, which formed a sort of pocket or pouch within the host’s peritoneal cavity. The alterations described in the epidermis were associated with the mechanical action of the isopod inside the pouc
Pollutant reduction and catalytic upgrading of a Venezuelan extra-heavy crude oil with Al2O3-supported NiW catalysts: Effect of carburization, nitridation and sulfurization
Get PDFAlumina-supported Ni-promoted W oxides, carbides and nitrides were presulfided and employed for reducing pollutants and increasing the quality of an extra-heavy crude oil during catalytic upgrading reactions. These materials were prepared by temperature programmed reaction using reactive gases and varying the (Ni/(Ni + W)) atomic ratio from 0.00 to 1.00. Catalysts were characterized by XRD, SEM, HRTEM and N2 physisorption. In order to study the effect of the atomic ratio in the conversion of the model molecule thiophene, room pressure HDS tests were used. The catalysts with best performances during thiophene HDS were tested in the upgrading of a Venezuelan extra-heavy crude oil characterized by having high asphaltenes, S and N contents, affecting competitiveness in the global market. These results were compared with a commercial NiMo catalyst. API gravity of crude oil, CHNS elemental analysis, 13C- and 1H NMR of crude oil and asphaltenic fraction, in addition to flocculation threshold of asphaltenes, were studied in order to verify variations in physicochemical properties of oil due to catalytic upgrading and to seek evidence of pollutants reduction and improvement of quality during this process. NiW catalysts with atomic ratio (Ni/(Ni + W) = 0.50 showed remarkable performance during thiophene HDS and heavy oil hydrotreatment, improving API gravity and reducing S content, modifying chemical nature of crude oil and asphaltenes, as it was revealed by results of elemental analysis, H/C ratio, flocculation threshold, Caro/Cali and Haro/Hali ratios. However, no significant variations were found in N contents of crudes and asphaltenes revealing poor HDN performance, apparently due to Na traces from the W precursor remaining in the final NiW catalysts.Elsevie
The importance of soils in predicting the future of plant habitat suitability in a tropical forest
Get PDFAims Assessment of the future of biodiversity under climate change has been based on climate-only models. We investigated the effects of including soil information when predicting future suitable areas for selected plant species in Amazonia. Methods We modelled current and future suitable habitats for 35 plant species and compared results of climate-only models with those obtained when climatic and edaphic variables were included. We considered six climatic scenarios for 2050 using different algorithms and projections of atmospheric CO2 concentration. Results Twenty-five species distribution models had an AUC > 0.69. Out of those, edaphic variables had the greatest contribution in 11 species models, while climatic variables were more important for 14 species. The inclusion of soil variables affected the size and shape of predicted suitable areas, especially in future models. For nearly half of the species, the size of future suitable areas were smaller in climate+soil models than predicted by climate-only models. Area reduction was more extreme in future scenarios with the higher level of CO2 concentration. Conclusions Our results highlight the importance of moving beyond climatic scenarios when modelling biodiversity responses to climate change. Failure to include soils in the models can overestimate future habitat suitability for many plant species.Kluwer Academic Publisher
Toxic Income as a Trigger of Climate Change
Get PDFThe rate of CO2 emissions concentration in the atmosphere increases the likelihood of significant impacts on humankind and ecosystems. The assumption that permissible levels of greenhouse gas emissions cannot exceed the global average temperature increase of 2 °C in relation to pre-industrial levels remains uncertain. Despite this uncertainty, the direct implication is that enormous quantities of fossil fuels have, thus far, wrongly been counted as assets by hydrocarbon firms as they cannot be exploited if we want to keep climate under certain control. These are the so-called “toxic assets”. Due to the relationship among CO2 emissions, GDP, energy consumption, and energy efficiency, the concept of toxic assets can be transferred to toxic income, which is the income level that would generate levels of CO2 emissions incompatible with keeping climate change under control. This research, using a simulation model based on country-based econometric models, estimated a threshold for income per capita above which the temperature limit of 2 °C would be surpassed. Under the business as usual scenario, average per capita income would be 13,433 (in constant 2010 USD) in 2036.MDP
Seasonal environmental parameters influence biochemical responses of the fiddler crab Minuca rapax to contamination in situ
Get PDFThe mudflat fiddler crab Minuca rapax, typical of mangroves and intertidal zones in the Western Atlantic Ocean, responds to fluctuations in environmental parameters by biochemical and physiological adjustments. Such biochemical effects are commonly employed in environmental studies as biomarkers of estuarine contamination. This study evaluates biochemical responses in the gills and hepatopancreas of M. rapax in situ from localities exhibiting different types and levels of contamination, against a backdrop of fluctuations in environmental parameters like salinity and temperature common to estuarine regions. The biochemical biomarkers metallothionein (MT)-like protein titers and glutathione S-transferase (GST), glutathione peroxidase (GPx) and acetylcholinesterase (AChE) activities were used to evaluate responses to environmental contamination and seasonal changes in environmental parameters. Crabs were collected during two seasons, the austral winter and summer, at three sites along the coast of the state of São Paulo, Brazil that present decreasing degrees of environmental contamination: Ilha Diana, Santos (ID) > Rio Itapanhaú, Bertioga (RI) > Picinguaba, Ubatuba (P), a pristine control site. Our findings show that MT were induced in crabs from the contaminated sites (ID and RI) mainly during winter, revealing the activation of detoxification mechanisms; however MT were also induced in P crabs during the summer rainy season. GPX, GST and AChE activities were altered in P crabs during summer and in ID and RI crabs in winter. While enzyme activities in summer crabs may reflect seasonal changes in precipitation and salinity, in winter these altered activities appear to reflect contamination, although an effect of environmental parameters cannot be excluded. These findings reveal a strong seasonal influence on biochemical biomarker responses in Minuca rapax, a relevant factor to consider when interpreting the impact of environmental contamination in estuaries