•Eddy covariance energy balance closure was investigated in a seasonally dry tropical forest.•Energy balance closure was better during the wet season.•The best energy balance closure occurred under ...very unstable conditions.•Under stable conditions the closure was poor, although the amount of information analyzed under this condition was reduced.•The largest portion of net radiation was converted into sensible heat flux, except during the wet season.
The energy balance closure obtained through the eddy covariance method is a problem which persists, despite advances in the development and improvement of instruments and recent efforts in the description of corrections and in the characterization of measuring uncertainties. In most places the sum of sensible and latent heat fluxes (H and λE) is less than available energy, i.e. the difference between net radiation (Rn) and soil heat flux (G). This study analyzed the annual and seasonal behavior of the energy partitioning and energy balance closure in the Caatinga Biome, which is a seasonally dry tropical forest located in the semiarid lands of Brazil, using the eddy covariance method. Results showed high seasonal variability in the energy partitioning. During the dry season, approximately 70% of Rn was converted into H and less than 5% of it was converted into latent heat flux (λE). During the wet season, the Rn portion converted into H and λE was similar: ˜ 40%. In annual terms, the Rn portion converted into H and λE was of the order of 50% and 20% respectively. The degree of the energy balance closure varied depending on the method used. When the closure was calculated using orthogonal regressions, the slope varied from 0.87 to 0.90 in 2014 and from 0.92 to 1.00 in 2015. However, when the closure was calculated by the energy balance ratio method, values varied from 0.70 to 0.79 in 2014 and from 0.73 to 0.82 in 2015. The closure was better in 2015 if compared to 2014 possibly due to the more intense turbulence observed in 2015 because friction velocity was higher than in 2014. The better closure in 2015 may also be associated with large eddies, which were more frequent in 2014 as evidenced by the correction coefficients for vertical wind velocity and water vapor and vertical wind velocity and sonic temperature. The energy balance closure was also analyzed considering atmospheric instability conditions and the best results were found under very unstable conditions, while the least expressive results were found under stable conditions. Under these conditions negative values of the energy balance ratio were also observed during dry and transition seasons, indicating that fluxes were reversed during these periods.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Resumo Este artigo apresenta resultados de uma pesquisa que buscou observar, nos diálogos constituídos pelo professor com um estudante da disciplina de Estágio Supervisionado com Ênfase no Ensino ...Fundamental II em um Vaivém, afirmações e indagações feitas por esse futuro professor que manifestaram evidências de que ele se autoavaliou. O Vaivém é um instrumento de avaliação que proporciona um diálogo personalizado entre professor e estudante acerca de assuntos referentes à Matemática, a aspectos relacionados ao ensino e a questões pessoais, quando utilizado em uma perspectiva de avaliação formativa. O estudante escolhido para ser analisado apresentou diferentes indícios de autoavaliação, revelando que assumiu o papel de avaliador propriamente dito na disciplina e não o de apenas um fornecedor de informações para o professor. Destacam-se, neste estudo, o papel do registro das autoanálises e autorreflexões e a importância de intervenções direcionadas à promoção da autoavaliação.
Abstract This article presents results of a research that sought to observe, in the dialogues constituted by the teacher with a student of the Supervised Internship with Emphasis on Elementary School II in a Vaivém , statements and questions made by this future teacher who showed some evidence that they used self-assessment. Vaivém is an assessment instrument that provides a personalized dialogue between teacher and student on issues related to mathematics, aspects related to teaching and personal issues, when used in a formative assessment perspective. The student chosen to be analyzed showed different signs of self-assessment, revealing that they assumed the role of evaluator in the discipline itself and not just a provider of information for the teacher. In this study, we highlight the role of recording self-analyses and self-reflections and the importance of interventions aimed at promoting self-assessment.
In recent years head-to-tail monoterpene geraniol has been widely explored as a potential anticancer agent. Natural analogs like alcohol nerol, aldehydes geranial, and neral have been investigated. ...We explored the synergism of these terpenes with clinically and non-clinically used compounds as potential candidates for treating different types of cancer. Promising activity for these compounds has also inspired new analog syntheses. The anticancer potential of these compounds is described in this review.
•Geraniol, nerol, geranial, and neral are active against many cancer cell lines.•Geraniol, nerol, geranial, and neral show selectivity to the cancer cells.•Monoterpenes geraniol and citral show synergism with known anticancer drugs.•Citral is active against breast cancer stem cells in vitro and ex vivo.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•In-situ observation of evapotranspiration (ET) in a Brazilian STDF (Caatinga) using eddy covariance.•Maximum surface conductance values occurred at approximately 09:00 (local time).•During the two ...studied years the surface did not decouple from the atmosphere.•During the wet season, ET was mainly controlled by available energy while surface conductance controlled ET during the dry season.
Seasonally dry tropical forests are among the most important biomes regarding regional and global hydrological and carbon fluxes. Thus, the objective of this study was to evaluate the seasonal and interannual variability of evapotranspiration (ET) and its biophysical control and characteristics (surface conductance—Gs; decoupling coefficient—Ω; ratio between actual evapotranspiration and equilibrium evapotranspiration—ET/ETeq) in a preserved Caatinga Biome environment during two dry years in the Northeast Brazil region. A study on this subject with this level of detail in this biome is unprecedent. Measurements were carried out using an eddy covariance system during the period from 1st January 2014 to 31st December 2015. The lowest ET values were observed in the dry season of both experiment years (0.3 and 0.2 mm day−1) as a consequence of poor water availability, which favored partial stomatal closure and reduced Gs values (0.22 and 0.13 mm s−1). The opposite occurred in the wet season, when ET (2.6 and 1.7 mm day−1) and Gs (3.74 and 2.13 mm s−1) means reached higher values. Regarding annual values, differences between total annual rainfall in both years is the most probable cause for the differences observed in annual ET values. In 2014, annual ET was of 473.3 mm while in 2015 it was 283.4 mm, which incurred in an overall decrease in Gs, Ω and ET/ETeq values. Leaf senescence and extremely low Gs values during the dry season suggest that the trees of the Caatinga Biome are more resilient regarding the use of water and are avoiding water stress caused under low water availability.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The analysis of gross primary production (GPP) is crucial to better understand CO2 exchanges between terrestrial ecosystems and the atmosphere, while the quantification of water-use efficiency (WUE) ...allows for the estimation of the compensation between carbon gained and water lost by the ecosystem. Understanding these dynamics is essential to better comprehend the responses of environments to ongoing climatic changes. The objective of the present study was to analyze, through AMERIFLUX and LBA network measurements, the variability of GPP and WUE in four distinct tropical biomes in Brazil: Pantanal, Amazonia, Caatinga and Cerrado (savanna). Furthermore, data measured by eddy covariance systems were used to assess remotely sensed GPP products (MOD17). We found a distinct seasonality of meteorological variables and energy fluxes with different latent heat controls regarding available energy in each site. Remotely sensed GPP was satisfactorily related with observed data, despite weak correlations in interannual estimates and consistent overestimations and underestimations during certain months. WUE was strongly dependent on water availability, with values of 0.95 gC kg−1 H2O (5.79 gC kg−1 H2O) in the wetter (drier) sites. These values reveal new thresholds that had not been previously reported in the literature. Our findings have crucial implications for ecosystem management and the design of climate policies regarding the conservation of tropical biomes, since WUE is expected to change in the ongoing climate change scenario that indicates an increase in frequency and severity of dry periods.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Este artigo apresenta resultados de uma pesquisa feita no Ensino Fundamental por meio da aplicação de uma Prova-Escrita-em-Fases, em uma perspectiva de avaliação como prática de investigação e como ...oportunidade de aprendizagem, com base em autores como Buriasco, Ferreira e Pedrochi Junior. Nesse instrumento, 36 estudantes do 6º e 7º anos do Ensino Fundamental tiveram a oportunidade de resolver 5 questões de matemática em 5 fases, contando com intervenções da professora regente, que também é autora deste artigo. À luz da Análise de Conteúdo, foram investigadas as produções escritas de um estudante. Pode-se observar que o instrumento possibilitou que o estudante modificasse suas respostas, repensando-as e que a Prova-Escrita-em-Fases auxilia na superação da dicotomia certo/errado. Palavras-chave: Educação matemática. Avaliação como prática de investigação. Avaliação como oportunidade de aprendizagem. Prova-escrita-em-fases.
No presente artigo, pretende-se discutir motivos que levaram membros do Grupo de Estudo e Pesquisa em Educação Matemática e Avaliação (GEPEMA) a produzirem seus trabalhos a respeito de Avaliação da ...Aprendizagem Escolar. Esta pesquisa qualitativa, de cunho teórico, utilizou como fonte os trabalhos de dissertação e tese dos membros do grupo, e a discussão dos trechos selecionados foi realizada pela perspectiva da Análise de Conteúdo. Observou-se que a escolha pelo tema dos trabalhos decorreu a partir de experiências vividas pelos pesquisadores, alguns como estudantes, outros como docentes, e tais experiências relatadas ocorreram desde a Educação Básica até cursos de Pós-Graduação, além de contatos com textos da área, com a orientadora ou com membros do grupo de pesquisa.
•Evapotranspiration and CO2 exchange were assessed in grazed pasture.•The seasonality of CO2 exchange was strongly agreement with rainfall seasonality.•Grazed tropical pasture acted as CO2 sink ...taking into account all uncertainties.•Averaged NEE 2 year was -230 ± 22 gC m−2 y−1.•WUE was similar to the values found in other pastures around the world.
Studies concerning the role of livestock farming on the regional budget of CO2 in Northeast of Brazil are scarce. Thus, our main objective was to evaluate the variability of CO2 exchange and evapotranspiration (ET) of a cultivated tropical forage C4 grass (Brachiaria brizantha) grazed by sheep for meat production. The experiment was conducted during the period from 2015-oct-01 to 2017-sep-30 using an eddy covariance flux tower. The pasture acted as a moderate CO2 sink, with mean annual net ecosystem exchange of -215 ± 22 g C m−2 y−1, while the average uncertainty associated with the calculation procedure was 15 g C m−2 ± 7.20% of NEP. The mean annual ET was 967 ± 245 mm. Carbon use efficiency at the ecosystem level was 0.20 ± 0.03, which is more efficient compared to similar experiments in grazed environments around the world. Water use efficiency at the ecosystem level was 1.14 ± 0.01 g C (kg H2O)−1.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Although seasonally dry tropical forests are considered invaluable to a greater understanding of global carbon fluxes, they remain as one of the ecosystems with the fewest observations. In this ...context, ecological and ecosystem models can be used as alternative methods to answer questions related to the interactions between the biosphere and the atmosphere in dry forests. The objective of this study was to calibrate the simple tropical ecosystem model (SITE) and evaluate its performance in characterizing the annual and seasonal behavior of the energy and carbon fluxes in a preserved fragment of the Caatinga biome. The SITE model exhibited reasonable applicability to simulate variations in CO2 and energy fluxes (r > 0.7). Results showed that the calibrated set of vegetation parameters adequately simulated gross primary productivity (GPP) and net ecosystem CO2 exchange (NEE). The SITE model was also able to accurately retrieve the time at which daily GPP and NEE peaked. The model was able to simulate the partition of the available energy into sensible and latent heat fluxes and soil heat flux when the calibrated parameters were used. Therefore, changes in the dynamics of dry forests should be taken into consideration in the modeling of ecosystem carbon balances.
Protein kinase M zeta, PKMζ, is a brain enriched kinase with a well characterized role in Long-Term Potentiation (LTP), the activity-dependent strengthening of synapses involved in long-term memory ...formation. However, little is known about the molecular mechanisms that maintain the tissue specificity of this kinase. Here, we characterized the epigenetic factors, mainly DNA methylation, regulating PKMζ expression in the human brain. The PRKCZ gene has an upstream promoter regulating Protein kinase C ζ (PKCζ), and an internal promoter driving PKMζ expression. A demethylated region, including a canonical CREB binding site, situated at the internal promoter was only observed in human CNS tissues. The induction of site-specific hypermethylation of this region resulted in decreased CREB1 binding and downregulation of PKMζ expression. Noteworthy, CREB binding sites were absent in the upstream promoter of PRKCZ locus, suggesting a specific mechanism for regulating PKMζ expression. These observations were validated using a system of human neuronal differentiation from induced pluripotent stem cells (iPSCs). CREB1 binding at the internal promoter was detected only in differentiated neurons, where PKMζ is expressed. The same epigenetic mechanism in the context of CREB binding site was identified in other genes involved in neuronal differentiation and LTP. Additionally, aberrant DNA hypermethylation at the internal promoter was observed in cases of Alzheimer's disease, correlating with decreased expression of PKMζ in patient brains. Altogether, we present a conserved epigenetic mechanism regulating PKMζ expression and other genes enhanced in the CNS with possible implications in neuronal differentiation and Alzheimer's disease.
Display omitted
•DNA methylation, of a CRE regulates the specific expression of PKMζ in human brain.•CRE site methylation regulates brain-specific expression of Long-term potentiation genes.•PKMζ expression decreases and promoter methylation increases in Alzheimer’s disease.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
