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981.
This paper looks at the interplay between human capital and innovation when climate and educational policies are implemented. Following recent empirical studies, human capital and general purpose research and development (R&D) are introduced in an integrated assessment model used to study the dynamics of climate change mitigation. Our results suggest that climate policy stimulates general purpose as well as clean R&D but reduces the incentive to invest in human capital formation. Both innovation and human capital have a scale effect, which increases pollution, as well as a technique effect, which saves emissions for each unit of output produced. While the energy-saving effect prevails when innovation increases, human capital is pollution-using, also because of the gross complementarity between the labor and energy input. When the role of human capital is the key input in the production of general purpose and energy knowledge is accounted for, the crowding-out of education induced by climate policy is mitigated, though not completely offset. By contrast, a policy mix that combines educational as well as climate objectives offsets the human capital crowding-out, at moderate and short-term costs. Over the long run, the policy mix leads to global welfare gains. 相似文献
982.
Peretyatko A Teissier S De Backer S Triest L 《Environmental monitoring and assessment》2012,184(3):1517-1531
Phytoplankton, zooplankton, submerged vegetation and main nutrients have been monitored in 48 eutrophic ponds from the Brussels
Capital Region (Belgium) between 2005 and 2008. Nine ponds have been biomanipulated in order to improve their ecological quality
and prevent the occurrence of noxious cyanobacterial blooms. The 4-year study of a large number of ponds allowed identification
of the factors having the strongest influence on phytoplankton growth. Continuous monitoring of the biomanipulated ponds allowed
the significance of changes caused by biomanipulation to be tested as well as the main reasons of biomanipulation successes
and failures to be elucidated. The main factors controlling phytoplankton in the ponds studied appeared to be grazing by large
cladocerans and inhibition of phytoplankton growth by submerged vegetation. Biomanipulation resulted in a significant decrease
in phytoplankton biomass in general and biomass of bloom-forming cyanobacteria in particular that were associated with a significant
increase in large Cladocera density and size. In six out of nine ponds biomanipulation resulted in the restoration of submerged
vegetation. The maintenance of the restored clearwater state in the biomanipulated ponds was strongly dependent on fish recolonisation
and nutrient level. In the absence of fish, the clearwater state could be maintained by submerged vegetation or large zooplankton
grazing alone. In case of fish recolonisation, restoration of extensive submerged vegetation could buffer, to a considerable
degree, the effect of fish except for ponds with high nutrient levels. 相似文献
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987.
Xinhua Fu V. Benno Meyer-Rochow John Tyler Hirobumi Suzuki Raphael De Cock 《Chemoecology》2009,19(3):155-168
Larval defensive behaviour and eversible organ morphology were compared in the firefly species Luciola cruciata Motschulsky 1854, L. lateralis Motschulsky 1860, L. leii Fu et Ballantyne 2006, Lampyris noctiluca Linnaeus 1767, Pyrocoelia analis Fabricius 1801, P. pectoralis Oliver 1883, P. sp. and two Diaphanes species. In all cases the eversible organs are located on the pleural cuticle, dorsal to the spiracle, but there is considerable
variation between species in their number, size and shape. In La. noctiluca they are confined to the abdomen, whereas in the other species they also occur on the meta- and mesothorax. In La. noctiluca and the Pyrocoelia species the organs are columnar in shape, contrasting with the forked organs of the Luciola and Diaphanes species. The eversible organs of the Luciola species, which are all aquatic, are remarkably larger (relative to body length) than those of the other, terrestrial species.
On organ eversion the Luciola species emit an odour resembling pine oil, the Diaphanes species smell weakly of mint and L. noctiluca and the Pyrocoelia species produce no discernible scent, though ants are nonetheless repelled by contact with everted L. noctiluca organs. The organs of all the species studied support protuberances on their external surface, though these too vary in shape,
size and ornamentation between species. In all species except L. noctiluca each protuberance is connected to a well-developed globular body via a long, thick stalk. Circular foveae are located in
the centres of these globular bodies. The globular bodies consist of secretory cells characterized by the presence of numerous
mitochondria and an extensive system of cisternae and tubular endoplasmic reticulum. Behavioural tests revealed that small
larvae run away instead of becoming immobile and glowing, whereas large larvae start to glow when disturbed. The study shows
that the eversible larval organs form an important part of a defensive arsenal in the Lampyridae. 相似文献
988.
Carl Van Colen J. Lenoir A. De Backer B. Vanelslander M. Vincx S. Degraer T. Ysebaert 《Marine Biology》2009,156(10):2161-2171
The role of multi-species benthic diatom films (BDF) in the settlement of late pediveliger larvae of the bivalve Macoma balthica was investigated in still-water bioassays and multiple choice flume experiments. Axenic diatom cultures that were isolated
from a tidal mudflat inhabited by M. balthica were selected to develop BDF sediment treatments characterized by a different community structure, biomass, and amount of
extracellular polymeric substances (EPS). Control sediments had no added diatoms. Although all larvae settled and initiated
burrowing within the first minute after their addition in still water, regardless of treatment, only 48–52% had completely
penetrated the high diatom biomass treatments after 5 min, while on average 80 and 69% of the larvae had settled and burrowed
into the control sediments and BDF with a low diatom biomass (<3.5 μg Chl a g−1 dry sediment), respectively. The percentage of larvae settling and burrowing into the sediment was negatively correlated
with the concentration of Chl a and EPS of the BDF. This suggests higher physical resistance to bivalve penetration by the BDF with higher diatom biomass
and more associated sugar and protein compounds. The larval settlement rate in annular flume experiments at flow velocities
of 5 and 15 cm s−1 was distinctly lower compared to the still-water assays. Only 4.6–5.8% of the larvae were recovered from BDF and control
sediments after 3 h. Nonetheless, a clear settlement preference was observed for BDF in the flume experiments; i.e., larvae
settled significantly more in BDF compared to control sediments irrespective of flow speed. Comparison with the settlement
of polystyrene mimics and freeze-killed larvae led to the conclusion that active selection, active secondary dispersal and,
at low flow velocities (5 cm s−1), passive adhesion to the sediment are important mechanisms determining the settlement of M. balthica larvae in estuarine biofilms. 相似文献
989.
Ying Hu Liu De Li Liu Min An Yin Lian Fu Ren Sen Zeng Shi Ming Luo Hanwen Wu Jim Pratley 《Ecological modelling》2009
Many plant species defend themselves against herbivorous insects indirectly by producing and releasing induced volatiles to attract natural enemies of the herbivores. In this paper, we consider the recruitment of natural enemies attracted by plant-induced volatiles and introduce the An–Liu–Johnson–Lovett model into the Lotka–Volterra model in an attempt to add this missing vital link in tritrophic interaction. Increase in attraction strength of plant-induced volatiles to the natural enemy leads to high fluctuation amplitude of plant biomass and herbivore population. When the attack strength of natural enemies reaches a certain level, fluctuation amplitude of plant biomass and herbivore population will decrease and plant biomass will approach to its environmental carrying capacity. The simulation demonstrates that plant volatile compounds induced by insects have led to the introduction of a third tritrophic level, e.g., natural enemies, into the plant–herbivore system, resulting in the coexistence of plants, insects, and natural enemies during the evolution process. 相似文献
990.