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161.
A range of new nanomaterials to replace the active materials in lithium ion batteries are currently being studied and employed in an attempt to overcome various performance limitations of previous technologies. Nanomaterial production and manufacturing techniques appear to fit into a general trend towards more energy intensive production methods for high-tech goods. This does not necessarily imply an increase in lifecycle energy use; artefacts that consume or transform energy during use could possibly regain this increased initial input via increased efficiency in use. In particular, this paper highlights that larger gains could be possible if the artefact in question allows a given service to be provided via an alternative and more efficient system entirely.The lifecycle energy efficiencies of lithium ion batteries constructed from several new advanced materials are analysed with several different system boundaries. Although nanomaterials require more energy input to produce, the implications of nanomaterials for energy flows in the use phase (i.e. driving), and higher levels such as the architecture of future transport fuel production systems are much larger in magnitude than the initial lifecycle inputs for producing the materials in question. 相似文献
162.
Thomas Merckx Ruth E. Feber Rebecca L. Dulieu Martin C. Townsend Mark S. Parsons Nigel A.D. Bourn Philip Riordan David W. Macdonald 《Agriculture, ecosystems & environment》2009,129(1-3):302-309
Agri-environment schemes (AES) are widely used policy instruments intended to combat widespread biodiversity declines across agricultural landscapes. Here, using a light trapping and mark-release-recapture study at a field-scale on nine common and widespread larger moth species, we investigate the effect of wide field margins (a popular current scheme option) and the presence of hedgerow trees (a potential scheme option in England) on moth abundance. Of these, we show that wide field margins positively affected abundances, although species did not all respond in the same way. We demonstrate that this variation can be attributed to species-specific mobility characteristics. Those species for which the effect of wide margins was strongest covered shorter distances, and were more frequently recaptured at their site of first capture. This demonstrates that the standard, field-scale uptake of AES may be effective only for less mobile species. We discuss that a landscape-scale approach, in contrast, could deliver significant biodiversity gains, as our results indicate that such an approach (perhaps delivered through targeting farmers to join AES) would be effective for the majority of wider countryside species, irrespective of their mobility level. 相似文献
163.
Demographic factors such as operational sex ratio (OSR) and local population density (LPD) are temporally and spatially dynamic in the natural environment but the influence of these variables on male mating success and the mechanisms behind it are still poorly understood and highly controversial. Here, we manipulated the OSR and LPD of a seed bug, Nysius huttoni, and carried out a series of mating trials to test how these variables affected male mating success. The two demographic factors had no significant interactions, suggesting that they affect male mating success independently in N. huttoni. In this species male mating success was significantly higher in both male- and female-biased OSR than in even OSR. It is suggested that, in male-biased OSR, the increased intensity of competition and interference does not result in lower male mating success; rather, males may make more effort in courting and females may have more chance to encounter better males, resulting in higher male mating success. In female-biased OSR, females may become less choosy and less likely to reject male mating attempt, leading to the higher male mating success. Lower male mating success in N. huttoni in high LPD may be due to increased interference between males and/or delayed female receptiveness for mating. OSR had a stronger effect on male mating success than LPD in N. huttoni, suggesting that OSR and LPD affect mating success in different ways and intensities. 相似文献
164.
Elena P. Kruchenkova Michael Goltsman Sergei Sergeev David W. Macdonald 《Die Naturwissenschaften》2009,96(4):457-466
The Arctic Fox Alopex lagopus semenovi population on Mednyi Island is completely isolated and subsists largely by scavenging on seabird colonies, which have remained
abundant and spatio-temporally predictable for many years. We compared population data at the beginning of 1976/1978 and some
time after 1994–2005, finding an 85% decline in fox numbers due to disease, to assess the effect of population size on social
structure. A total of 81 groups of known size and composition was observed during this 29-year period. Overall, helpers (usually
non-lactating yearling females) occurred in 25.7% of groups, and in 32.4% of groups there were two or three lactating females.
Female engagement in alloparental behaviour decreased, but not statistically significantly, after the decline in population
density. Total food availability was apparently constant throughout the study period, and therefore, the amount available
per individual was much higher later in the study. Both communally nursing females and helpers brought food and helped to
guard the litter. However, the benefits of communal rearing were unclear. While cubs were left without guards significantly
more rarely in the groups with an additional adult, the number of cubs weaned per lactating female was greater in groups with
one (3.93 ± 1.60), as opposed to two or three (3.06 ± 0.92), lactating females. Survival of cubs to 1 year of age in the groups
with two lactating females and/or with helpers was lower than that in the families with one lactating female without helpers (22.2% vs 32.2%). Fewer second-generation litters were
born to foxes produced by composite families than to those produced by pairs. Reproductive adults producing by pairs had,
on average, 1.23 (±1.72) second-generation litters. In groups that initially included additional adults, the average number
of second-generation litters per reproductive female was 0.21 (±0.49) and 0.46 (±0.81) litters per male. Thus, according to
three measures, increased group size had no apparent positive impact on reproductive success. The increased parental investment
and enhanced guarding of the cubs in the larger families could be beneficial under conditions of high population density and
a saturated biotope to which the island fox population was presumably adapted before the population crash in the late 1970s. 相似文献
165.
Angus H. H. Macdonald Eugenia M. Sampayo Tyrone Ridgway Michael H. Schleyer 《Marine Biology》2008,154(2):209-217
Studies on latitudinal gradients in Symbiodinium diversity on scleractinian corals are largely restricted to warm-water low latitude locations, and it appears that there
is a shift in symbiont distributions with increasing latitude. The Symbiodinium assemblages of high latitude coral communities have largely been undocumented despite occupying an important transitional
zone between tropical and temperate regions. Using a combination of the internal transcribed spacer region 2 (ITS2) and denaturing
gradient gel electrophoresis (DGGE), we assessed the cladal and subcladal variability of Symbiodinium in the widely distributed species Stylophora pistillata along a latitudinal transect in southeast African waters which extended into high latitude locations. All colonies examined
belonged to clade C. Six unique ITS2-DGGE banding profiles (designated Cspa to Cspf) were observed, which showed a latitudinal distribution from north to south, most likely a result of a gradient in water
temperature and irradiance driven by riverine input in the southern regions. Sequence analysis revealed that all sequences
except one did not match previously identified clade C sub-types, probably due to the lack of regional information in the
Western Indian Ocean when compared to the Caribbean and Pacific. This study further supports the applicability of ITS2-DGGE
in studies on Symbiodinium diversity, and highlights that potentially ecologically informative biogeographic patterns may be overlooked when only cladal
designations are employed. 相似文献
166.
Lifetime reproductive success and composition of the home range in a large herbivore 总被引:3,自引:0,他引:3
McLoughlin PD Gaillard JM Boyce MS Bonenfant C Messier F Duncan P Delorme D Van Moorter B Saïd S Klein F 《Ecology》2007,88(12):3192-3201
The relationship between individual performance and nonrandom use of habitat is fundamental to ecology; however, empirical tests of this relationship remain limited, especially for higher orders of selection like that of the home range. We quantified the association between lifetime reproductive success (LRS) and variables describing lifetime home ranges during the period of maternal care (spring to autumn) for 77 female roe deer (Capreolus capreolus) at Trois-Fontaines, Champagne-Ardenne, France (1976-2000). We maintained population growth rate (adjusted to account for removals of non-focal animals) near rmax, which enabled us to define the fitness-habitat relationship in the absence of density effects. Using a negative binomial model, we showed that a roe deer's incorporation into its home range of habitat components important to food, cover, and edge (meadows, thickets, and increased density of road allowances) was significantly related to LRS. Further, LRS decreased with increasing age of naturally reclaimed meadows at the time of a deer's birth, which may have reflected a cohort effect related to, but not entirely explained by, a decline in quality of meadows through time. Predictive capacity of the selected model, estimated as the median correlation (rs) between predicted and observed LRS among deer of cross-validation samples, was 0.55. The strength of this relationship suggests that processes like selection of the site of a home range during dispersal may play a more important role in determining fitness of individuals than previously thought. Individual fitness of highly sedentary income breeders with high reproductive output such as roe deer should be more dependent on home range quality during the period of maternal care compared to capital breeders with low reproductive output. Identification of the most important habitat attributes to survival and reproduction at low density (low levels of intraspecific competition) may prove useful for defining habitat value ("intrinsic habitat value"). 相似文献
167.
The use of geographic information systems (GIS) technology in natural resource management has expanded rapidly: It is the
preferred tool of spatial data analysis addressing large landscapes and is typically the presentation medium for conveying
landscape-scale scientific findings to all kinds of audiences. In a case study using the Coastal Landscape Analysis and Modeling
Study in western Oregon, it was found that the use of GIS to analyze and display natural resource data in that project produced
a variety of responses among different participants and participant groups. The findings offer insights into the workings
of groups attempting public involvement in natural resource management. 相似文献
168.
Temperature measurements were taken at three pilot-scale facultative ponds located at Esholt wastewater treatment works in West Yorkshire, UK over two one-year periods. The measurements were taken at different depths using a technology called Thermochron iButton. The iButton readings were compared with temperature measurements taken by a YSI sonde probe and maximum/minimum thermometers: they were found to be within 1 .C. In the temperature range 3.18 .C the mean weekly and monthly air temperatures were found to be good predictors for the mean weekly and monthly pond water-column temperatures. The level of stratification in the ponds under UK climatic conditions was assessed; the data revealed that the ponds remained thermally stratified for significant periods during the year despite their shallow depth. 相似文献
169.
Macdonald NW Rediske RR Scull BT Wierzbicki D 《Journal of environmental quality》2008,37(5):1974-1985
Municipal solid waste landfill leachate must be removed and treated to maintain landfill cover integrity and to prevent contamination of surface and ground waters. From 2003 to 2007, we studied an onsite disposal system in Ottawa County, Michigan, where leachate was spray irrigated on the vegetated landfill cover. We established six 20-m-diameter circular experimental plots on the landfill; three were spray irrigated as part of the operational system, and three remained as untreated control plots. We quantified the effects of leachate application on soil properties, soil solution chemistry, vegetative growth, and estimated solute leaching. The leachate had high mean levels of electrical conductivity (0.6-0.7 S m(-1)), Cl (760-900 mg L(-1)), and NH(4)-N (290-390 mg L(-1)) but was low in metals and volatile organic compounds. High rates of leachate application in 2003 (32 cm) increased soil electrical conductivity and NO(3)-N leaching, so a sequential rotation of spray areas was implemented to limit total leachate application to <9.6 cm yr(-1) per spray area. Concentrations of NO(3)-N and leaching losses remained higher on irrigated plots in subsequent years but were substantially reduced by spray area rotation. Leachate irrigation increased plant biomass but did not significantly affect soil metal concentrations, and plant metal concentrations remained within normal ranges. Rotating spray areas and timing irrigation to conform to seasonal capacities for evapotranspiration reduced the localized impacts of leachate application observed in 2003. Careful monitoring of undiluted leachate applications is required to avoid adverse impacts to vegetation or soils and elevated solute leaching losses. 相似文献
170.
The impact of dominant trends in public administration, such as decentralisation and privatisation on complex collective challenges is insufficiently understood. This is relevant in settings where climate change impacts become manifest at local level, and where financing power resides at national level but decisions are made more locally in a fragmented institutional setting. This study assists in overcoming this gap by analysing how the institutional context (i.e. a decentralised, privatised, fragmented setting) influences the capacity to address climate change challenges in a vulnerable area (the South Devon coast in the UK). There has been little action to address expected climate change impacts in this vulnerable stretch of coast. A lack of clarity around responsibility for addressing climate impacts and a lack of a deliberative structure between various actors involved, within a context of austerity, hamper climate change adaptation. The findings question whether decentralised decision making is sufficient for addressing climate adaptation challenges. 相似文献