188 research outputs found
Collection Auguste Rondel au département des arts du spectacle de la bibliothèque nationale (La)
Deuxième journée d\u27études de la section des Bibliothèques-Musées des Arts du Spectacle (La)
Soil structure and earthworm activity under different tillage systems in organic farming
Organic farmers are encouraged to adopt conservation tillage to preserve soil quality and fertility and prevent erosion. However, many studies in different soil and climate conditions have demonstrated that the compaction of the untilled layer is higher in conservation tillage than in conventional tillage. As earthworm activity may help alleviate soil compaction in organic farming, the impact on the soil structure and earthworm population and activity was studied for 4 different tillage managements (1) mouldboard ploughing (MP), (2) shallow ploughing (SP), (3) reduced tillage (RT) and (4) no-tillage (NT), in 3 french areas. The first results are: (1) MP soil structure is better than SP, RT and NT, (2) water infiltration is higher at soil surface in SP, RT and NT, lower at 17 cm depth, (3) more earthworms, especially anecic species, are found in NT, (4) but more opening channels are found in MP. Then, during the first years of transition from MP to NT, soil structure is better in MP, and whereas earthworm numbers is reduced, it favours earthworm activity
Thermodynamic performance bounds for radiative heat engines
This paper discusses the performance limits of heat engines exchanging heat
radiatively with a hot source while in thermal contact with a cold sink.
Starting from solar energy conversion models, we derive power-versus-efficiency
upper bounds for both reciprocal and nonreciprocal radiative heat engines. We
find that nonreciprocal engines may allow significantly better performance than
reciprocal ones, particularly for low emitter temperatures or when operating
close to Carnot efficiency. The results give valuable guidelines for the design
and optimization of thermophotovoltaic systems.Comment: 6 pages, 5 figure
In vivo evaluation of intracellular drug-nanocarriers infused into intracranial tumours by convection-enhanced delivery: Distribution and radiosensitisation efficacy
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