Relocation in Carsharing Systems using Flows in Time-Expanded Networks

A manuscript on this topic can be found at: http://hal.archives-ouvertes.fr/hal-00908242International audienceIn a carsharing system, a fleet of cars is distributed at stations in an urban area, customers can take and return cars at any time and station, provided that there is a car available at the start station and a free place at the final station. To ensure the latter, customers have to book their demands in advance; hereby, customer requests can be accepted or rejected by the operator. The stations have to keep a good ratio between available cars and free places in each station, in order to serve already accepted customer requests and to refuse as few new customer requests as possible. This leads to the problem of relocating cars between stations, which can be modeled as Pickup and Delivery Problem in a metric space induced by the urban area or, alternatively, by means of flows of cars in convoys in a time-expanded network.Note that we consider an innovative carsharing system with partly autonomous cars which allows to build convoys of cars, each moved by only one driver. This leads to a similar situation as in bikesharing systems, where trucks can simultaneously move several bikes, but no requests are booked in advance. Hereby, two flows are coupled in the sense that the flow of cars is dependent from the flow of drivers (since cars can only be moved in convoys); the flow coupling constraints reflect the complexity of the studied problem.We present integer programming formulations for two variants of the relocation problem: a min-cost flow problem to serve a given set of customer requests at minimal costs (quality of service aspect), and a max-profit flow problem to additionally solve the decision problem of accepting or rejecting customer requests (economic aspect). Both models take advantage of users booking their demands in advance and can be applied to the offline as well as the online version of the relocation problem in order to fully capture the dynamic evolution of the system over time.</p

Avaliação de clones de cupuacuzeiro (Theobroma grandiflorum (Willd. ex Spreng) K. Schumm.) quanto a tolerância a vassoura-de-bruxa (Crinipellis perniciosa (Stahel) Singer).

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Reporting transparency: making the ethical mandate explicit.

Improving the transparency and quality of reporting in biomedical research is considered ethically important; yet, this is often based on practical reasons such as the facilitation of peer review. Surprisingly, there has been little explicit discussion regarding the ethical obligations that underpin reporting guidelines. In this commentary, we suggest a number of ethical drivers for the improved reporting of research. These ethical drivers relate to researcher integrity as well as to the benefits derived from improved reporting such as the fair use of resources, minimizing risk of harms, and maximizing benefits. Despite their undoubted benefit to reporting completeness, questions remain regarding the extent to which reporting guidelines can influence processes beyond publication, including researcher integrity or the uptake of scientific research findings into policy or practice. Thus, we consider investigation on the effects of reporting guidelines an important step in providing evidence of their benefits

Widespread forest vertebrate extinctions induced by a mega hydroelectric dam in lowland Amazonia

Mega hydropower projects in tropical forests pose a major emergent threat to terrestrial and freshwater biodiversity worldwide. Despite the unprecedented number of existing, underconstruction and planned hydroelectric dams in lowland tropical forests, long-term effects on biodiversity have yet to be evaluated. We examine how medium and large-bodied assemblages of terrestrial and arboreal vertebrates (including 35 mammal, bird and tortoise species) responded to the drastic 26-year post-isolation history of archipelagic alteration in landscape structure and habitat quality in a major hydroelectric reservoir of Central Amazonia. The Balbina Hydroelectric Dam inundated 3,129 km2 of primary forests, simultaneously isolating 3,546 land-bridge islands. We conducted intensive biodiversity surveys at 37 of those islands and three adjacent continuous forests using a combination of four survey techniques, and detected strong forest habitat area effects in explaining patterns of vertebrate extinction. Beyond clear area effects, edge-mediated surface fire disturbance was the most important additional driver of species loss, particularly in islands smaller than 10 ha. Based on species-area models, we predict that only 0.7% of all islands now harbor a species-rich vertebrate assemblage consisting of ≥80% of all species. We highlight the colossal erosion in vertebrate diversity driven by a man-made dam and show that the biodiversity impacts of mega dams in lowland tropical forest regions have been severely overlooked. The geopolitical strategy to deploy many more large hydropower infrastructure projects in regions like lowland Amazonia should be urgently reassessed, and we strongly advise that long-term biodiversity impacts should be explicitly included in pre-approval environmental impact assessments

Reação de espécies de Piper a dois isolados de Nectria haematococca f. sp. piperis.

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Fungos associados às sementes de tento e maranhoto.

A utilização de sementes sadias é fundamental para o sucesso de um empreendimento florestal. O objetivo deste trabalho foi identificar e quantificar os fungos associados às sementes de tento (Ormosia sp.) e maranhoto (Phyllanthus nobilis (L. f.) Müll. Arg). Os experimentos foram realizados no Laboratório de Fitopatologia da Embrapa Amazônia Oriental, em Belém, Pará. As sementes testadas foram cedidas pelo Laboratório de Sementes Florestais da Embrapa Amazônia Oriental. Foram analisadas 50 sementes de tento e 50 de maranhoto, originárias de Belterra e Bonito, estado do Pará. As amostras foram divididas em sub-amostras de 25 sementes, com e sem assepsia, para realização dos testes de sanidade em meio de cultura de Batata-Dextrose-Agar (BDA). As sementes contaminadas foram analisadas e lâminas das culturas fúngicas foram avaliadas sob microscópio óptico. Aspergillus sp. foi o único fungo detectado nas duas espécies. A infestação nas sementes de maranhoto e tento, com assepsia, foi de 8% e 36%, enquanto que, nas sem assepsia, foi de 80% e 44%, respectivamente. A assepsia utilizada nos ensaios (hipoclorito de sódio a 1%, por cinco minutos) mostrou maior eficiência nas sementes de maranhoto do que de nas de tento, visto que nestas últimas o índice de infestação por Aspergillus foi considerado alto quando comparado com o tratamento sem assepsia