Quantum control theory for coupled 2-electron dynamics in quantum dots

We investigate optimal control strategies for state to state transitions in a model of a quantum dot molecule containing two active strongly interacting electrons. The Schrodinger equation is solved nonperturbatively in conjunction with several quantum control strategies. This results in optimized electric pulses in the THz regime which can populate combinations of states with very short transition times. The speedup compared to intuitively constructed pulses is an order of magnitude. We furthermore make use of optimized pulse control in the simulation of an experimental preparation of the molecular quantum dot system. It is shown that exclusive population of certain excited states leads to a complete suppression of spin dephasing, as was indicated in Nepstad et al. [Phys. Rev. B 77, 125315 (2008)].Comment: 24 pages, 9 figure

Relações hídricas do açaizeiro em mata de várzea do estuário do Amazonas.

As relações hídricas do açaizeiro(Euterpe oleracea Mart.) foram avaliadas em plantas adultas, vegetando em ecossistemas típicos de mata inundável do estuário amazônico, com o objetivo de verificar os possíveis efeitos da inundação periódica total ou parcial dos sistemas radiculares e de outros fatores ambientais sobre o fluxo de água no sistema solo-planta-atmosfera. Foram avaliados, nas épocas chuvosa e seca, a condutância estomática ao fluxo de vapor d?água, o potencial hídrico foliar, o teor relativo de água dos tecidos foliares e o teor relativo de água no ponto de perda de turgor dos tecidos dos folíolos, relacionando-os com o défice de pressão de vapor d?água da atmosfera (DPV), radiação solar e altura das marés. O açaizeiro tem uma condutância máxima baixa (0,160 mol.m-2.s-1) em relação a outras palmeiras e os seus estômatos respondem mais à radiação solar do que ao DPV. Observou-se também que a espécie é adaptada a ambientes de hipoxia do sistema radicular e que as inundações periódicas, por efeito das marés, não afetam a absorção de água pelas raízes. Também na época seca (estação das marés baixas), esta espécie mantem a absorção de água em níveis suficientes para suprir a demanda transpiratória

De que modo o el niño influência a Amazônia? um experimento de exclusão de chuva.

Org. por Taciana Barbosa Cavalcanti e Bruno Machado Teles Walter

Throughfall reduction: Impacts on solution nutrient fluxes.

Oral 399. Disponível também on-line

21st Century drought-related fires counteract the decline of Amazon deforestation carbon emissions

Tropical carbon emissions are largely derived from direct forest clearing processes. Yet, emissions from drought-induced forest fires are, usually, not included in national-level carbon emission inventories. Here we examine Brazilian Amazon drought impacts on fire incidence and associated forest fire carbon emissions over the period 2003–2015. We show that despite a 76% decline in deforestation rates over the past 13 years, fire incidence increased by 36% during the 2015 drought compared to the preceding 12 years. The 2015 drought had the largest ever ratio of active fire counts to deforestation, with active fires occurring over an area of 799,293 km2. Gross emissions from forest fires (989 ± 504 Tg CO2 year−1) alone are more than half as great as those from old-growth forest deforestation during drought years. We conclude that carbon emission inventories intended for accounting and developing policies need to take account of substantial forest fire emissions not associated to the deforestation process

Framing REDD+ in the Brazilian national media: how discourses evolved amid global negotiation uncertainties

Reducing emissions from deforestation and degradation (REDD+) in tropical countries is an important and contested element of the post-Kyoto climate regime. For policy options which generate controversy between diverse actor groups, such as REDD+, mass media plays an important role in defining and supporting policy possibilities. Analysis of the way in which national media frames issues of climate change and deforestation can offer insights into the nature of the contested domains of the REDD+ policy process. Here, we examine the Brazilian national media discourses surrounding REDD+ because it contributes to setting the tone of policy debates at the federal level. Specifically, we ask the following: (i) How was REDD+ portrayed in the Brazilian national print media and whose opinions and perceptions were represented? and (ii) How have media frames on REDD+ in the national print media changed over time? Our results contribute with new knowledge for understanding the observed progress of REDD+ in Brazil. We identify two main themes that dominate the focus in the national media coverage of REDD+, specifically “politics and policymaking” (representing half the coverage) and “economics and market” (with over a third). Results show that discussions around carbon markets were amongst the most contested and that optimism in relation to REDD+ effectiveness declined over time. The analysis suggests that positions adopted on the national REDD+ strategy were shaped by state and federal collision of interests. We demonstrate an evolution of national concerns from an initial focus on efficiency (e.g. finance and carbon markets) to a recentred focus on equity issues (e.g. implementation of safeguards). We conclude with some thoughts on the implications of these features for REDD+ interventions and implementation in Brazil