208 research outputs found
Composição e abundĂąncia de peixes da interface entre as ĂĄguas abertas e bancos de macrĂłfitas e sua dinĂąmica nos perĂodos de crepĂșsculos matutino e vespertino, no lago CatalĂŁo, Amazonas, Brasil (Composition and abundance of fishes in the interface between open water and macrophyte banks, and the dynamics of this interface during morning and evening twilight, in lake Catalao, Amazonas, Brazil)
This work studied the composition and abundance of the fishes that move between macrophyte
banks and open water during the morning twilight (CM) and afternoon twilight (CV). The collections
were made using gillnets, along banks of Paspalum repens, at CatalĂŁo lake, in Amazonas, Brazil. A
total of 222 individuals and 37 species were collected. Of these, 130 individuals were collected
during the CM and 92 during the CV; 80 individuals were leaving during the CM and 40 individuals
were leaving during the CV. Auchenipterus nuchalis, Pellona castelnaeana, Triportheus angulatus and
T. albus were the most common and concentrated species collected in the CM and Pimelodus blochii
was the most common species collected in the CV
Stand dynamics modulate water cycling and mortality risk in droughted tropical forest
This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Transpiration from the Amazon rainforest generates an essential water source at a global and local scale. However, changes in rainforest function with climate change can disrupt this process, causing significant reductions in precipitation across Amazonia, and potentially at a global scale. We report the only study of forest transpiration following a long-term (>10 year) experimental drought treatment in Amazonian forest. After 15 years of receiving half the normal rainfall, drought-related tree mortality caused total forest transpiration to decrease by 30%. However, the surviving droughted trees maintained or increased transpiration because of reduced competition for water and increased light availability, which is consistent with increased growth rates. Consequently, the amount of water supplied as rainfall reaching the soil and directly recycled as transpiration increased to 100%. This value was 25% greater than for adjacent nondroughted forest. If these drought conditions were accompanied by a modest increase in temperature (e.g., 1.5°C), water demand would exceed supply, making the forest more prone to increased tree mortality.This work is a product of UK NERC grant NE/J011002/1 to PM and MM, CNPQ grant 457914/2013-0/MCTI/CNPq/FNDCT/LBA/ESECAFLOR to ACLD, an ARC grant FT110100457 to PM and a UK NERC independent fellowship grant NE/N014022/1 to LR. It was previously supported by NERC NER/A/S/2002/00487, NERC GR3/11706, EU FP5-Carbonsink and EU FP7-Amazalert to PM. RP acknowledges support of MINECO (Spain), grant CGL2014-5583-JIN
Amazonian trees have limited capacity to acclimate plant hydraulic properties in response to longâterm drought
This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordThe fate of tropical forests under future climate change is dependent on the capacity of their trees to adjust to drier conditions. The capacity of trees to withstand drought is likely to be determined by traits associated with their hydraulic systems. However, data on whether tropical trees can adjust hydraulic traits when experiencing drought remain rare. We measured plant hydraulic traits (e.g. hydraulic conductivity and embolism resistance) and plant hydraulic system status (e.g. leaf water potential, native embolism and safety margin) on >150 trees from 12 genera (36 species) and spanning a stem size range from 14 to 68 cm diameter at breast height (DBH) at the world's only longârunning tropical forest drought experiment. Hydraulic traits showed no adjustment following 15 years of experimentally imposed moisture deficit. This failure to adjust resulted in these droughtâstressed trees experiencing significantly lower leaf water potentials, and higher, but variable, levels of native embolism in the branches. This result suggests that hydraulic damage caused by elevated levels of embolism is likely to be one of the key drivers of droughtâinduced mortality following longâterm soil moisture deficit. We demonstrate that some hydraulic traits changed with tree size, however, the direction and magnitude of the change was controlled by taxonomic identity. Our results suggest that Amazonian trees, both small and large, have limited capacity to acclimate their hydraulic systems to future droughts, potentially making them more at risk of droughtâinduced mortality.Natural Environment Research Council (NERC)Brazilian Higher Education Coordination Agency (CAPES)Royal SocietyEuropean Union FP7ARCFAPESP/Microsof
The effects of rainfall and vegetation on litterfall production in the semiarid region of northeastern Brazil
Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at â s = 8 TeV with the ATLAS detector
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fbâ1 of â s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente
Integrated Environmental Assessment of streams in the Sinos River basin in the state of Rio Grande do Sul, Brazil
Individual-environment interactions in swimming: The smallest unit for analysing the emergence of coordination dynamics in performance?
Displacement in competitive swimming is highly dependent on fluid characteristics,
since athletes use these properties to propel themselves. It is essential for sport
scientists and practitioners to clearly identify the interactions that emerge between
each individual swimmer and properties of an aquatic environment. Traditionally, the
two protagonists in these interactions have been studied separately. Determining the
impact of each swimmerâs movements on fluid flow, and vice versa, is a major
challenge. Classic biomechanical research approaches have focused on swimmersâ
actions, decomposing stroke characteristics for analysis, without exploring
perturbations to fluid flows. Conversely, fluid mechanics research has sought to
record fluid behaviours, isolated from the constraints of competitive swimming
environments (e.g. analyses in two-dimensions, fluid flows passively studied on
mannequins or robot effectors). With improvements in technology, however, recent
investigations have focused on the emergent circular couplings between swimmersâ
movements and fluid dynamics. Here, we provide insights into concepts and tools that
can explain these on-going dynamical interactions in competitive swimming within
the theoretical framework of ecological dynamics
Natural products: an extraordinary source of value-added compounds from diverse biomasses in Brazil
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