718 resultados para Weak sustainability
Resumo:
Games that simulate complex realities to be dealt with in teams are an effective tool for fostering interactive learning processes. they link different levels of decision-making in the household, community and societal contexts. Negotiation and harmonisation of different perceptions and interests, be it within or between different households, form the basis of a common strategy for sustainable development.
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Weak radiative decays of the B mesons belong to the most important flavor changing processes that provide constraints on physics at the TeV scale. In the derivation of such constraints, accurate standard model predictions for the inclusive branching ratios play a crucial role. In the current Letter we present an update of these predictions, incorporating all our results for the O(α2s) and lower-order perturbative corrections that have been calculated after 2006. New estimates of nonperturbative effects are taken into account, too. For the CP- and isospin-averaged branching ratios, we find Bsγ=(3.36±0.23)×10−4 and Bdγ=(1.73+0.12−0.22)×10−5, for Eγ>1.6 GeV. Both results remain in agreement with the current experimental averages. Normalizing their sum to the inclusive semileptonic branching ratio, we obtain Rγ≡(Bsγ+Bdγ)/Bcℓν=(3.31±0.22)×10−3. A new bound from Bsγ on the charged Higgs boson mass in the two-Higgs-doublet-model II reads MH±>480 GeV at 95% C.L.
Resumo:
Lake Victoria is Africa’s single most important source of inland fishery production. After it was initially fished down in the first half of the 20th century, Lake Victoria became home to a series of introduced food fishes, culminating in the eventual demographic dominance of the Nile perch, Lates niloticus. Simultaneously with the changes in fish stocks, Lake Victoria experienced dramatic changes in its ecology. The lake fishery during most of the 20th century was a multispecies fishery resting on a diverse lake ecosystem, in which native food fishes were targeted. The lake ended the century with a much more productive fishery, but one in which three species — two of them introduced — made up the majority of the catch. Although many fish stocks in Lake Victoria had declined before the expansion of the Nile perch population, a dramatic increase in the population size of Nile perch in the 1980s roughly coincided with the drastic decline or disappearance of many indigenous species. Now, two decades after the rise of Nile perch in Lake Victoria, this species has shown signs of being overfished, and some of the native species that were in retreat — or even thought extinct — are now reemerging. Data on the resurgence of the indigenous species suggest that heavy fishing of Nile perch may enhance biodiversity; this has spawned renewed interest in management options that promote both fishery sustainability and biodiversity conservation.
Resumo:
Description of ALS background, concept, didactic guidelines and thematic sheets, in Portuguese.
Resumo:
The interaction of a comet with the solar wind undergoes various stages as the comet’s activity varies along its orbit. For a comet like 67P/Churyumov–Gerasimenko, the target comet of ESA’s Rosetta mission, the various features include the formation of a Mach cone, the bow shock, and close to perihelion even a diamagnetic cavity. There are different approaches to simulate this complex interplay between the solar wind and the comet’s extended neutral gas coma which include magnetohydrodynamics (MHD) and hybrid-type models. The first treats the plasma as fluids (one fluid in basic single fluid MHD) and the latter treats the ions as individual particles under the influence of the local electric and magnetic fields. The electrons are treated as a charge-neutralizing fluid in both cases. Given the different approaches both models yield different results, in particular for a low production rate comet. In this paper we will show that these differences can be reduced when using a multifluid instead of a single-fluid MHD model and increase the resolution of the Hybrid model. We will show that some major features obtained with a hybrid type approach like the gyration of the cometary heavy ions and the formation of the Mach cone can be partially reproduced with the multifluid-type model.
Resumo:
The concept of digital sustainability is mentioned in research on digital preservation as well as on openness topics. Both streams of literature point out the necessary discussion how to create, use, and regulate digital resources in order to maximize their value for our society today and in the future. This paper therefore reviews current work on digital sustainability, presents a list of six charac-teristics how to define digitally sustainable goods, and draws the link to aspects of e-government.
Resumo:
The Sustainable Development Goals (SDGs) present the new global agenda by the United Nations for the next 15 years from 2016 to 2030. In this research paper we examine how digital resources may contribute to the achievement of the SDGs. Based on a broad literature review we argue functional digital sustainability supports the SDGs while discrete digital sustainability is required to create and progress knowledge necessary to advance the SDGs. First we explain the perspectives of functional and discrete sustainability; secondly we map the two perspectives onto the 17 SDGs with examples incorporating both perspectives of digital sustainability. We conclude that digital sustainability should encompass both perspectives in order to exploit the full potential of information systems in regard to sustainability transformations.