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521.
522.
I. Anna S. Olsson Christian Gamborg Peter Sandøe 《Journal of Agricultural and Environmental Ethics》2006,19(1):37-46
Animal welfare and the ethical issues it raises have been discussed intensively for a couple of decades. The emphasis has
been on the direct effects of housing and husbandry, but more attention is now being given to problems originating in selective
breeding. European attempts to adjust animal welfare legislation to deal with these problems have been largely unsuccessful,
but the fact that selective breeding can introduce welfare problems continues to place an ethical responsibility on the animal
breeding industry. Since breeding decisions are made centrally and, increasingly, internationally, strategic change is only
likely to occur if it is embedded in an international agreement of some kind. The aim of this paper is to describe the key
ethical issues facing animal breeding and assess the suggestion that the breeding industry itself can deal with ethical issues
by means of an ethical code. Results from recent projects involving commercial breeding enterprises are presented. 相似文献
523.
Using the hedonic pricing approach, this paper investigates how the information released on public registries of contaminated and potentially contaminated sites affects nearby commercial and industrial properties in Baltimore, Maryland. The study found that industrial properties are virtually unaffected by proximity to a site with a history of contamination, while commercial properties do suffer an external cost due to the proximity to a contaminated site. This external cost is not cleared once the site has been cleaned up or has been pronounced to be harmless. It also found that the impacts of urban economic development policies, such as Empowerment Zones and Enterprise Zones, have had positive effects on industrial property values, but less so on commercial properties. In sum, brownfield properties in Baltimore are not particularly attractive investments for developers, and there is little potential for self-sustaining clean-up based on appropriate fiscal incentives, such as Tax Increment Financing. It is doubtful that ‘one size fits all’ measures to encourage the clean-up of contaminated sites can be successful in this context. 相似文献
524.
The olfactory circuitry of Drosophila melanogaster is becoming increasingly clear. However, how olfactory processing translates into appropriate behavioral responses is still
poorly understood. Using a sibling species approach, we tested how a perturbation in the olfactory circuitry affects odor
preference. In a previous study, we found that the sibling species of D. melanogaster, the specialist D. sechellia, overrepresents a sensillum, ab3, the A neuron of which is sensitive to hexanoate esters, characteristic of the species’
sole host, the Morinda citrifolia fruit. Concordantly, the corresponding glomerulus, DM2, is enlarged. In this study, we found that the ab3B neuron, the expansion
of which was previously assumed to be pleiotropic and of no ecological significance, is in fact tuned to another morinda fruit
volatile, 2-heptanone (HP). Axons of this neuron type arborize in a second enlarged glomerulus. In behavioral experiments
we tested how this has affected the fly’s odor preference. We demonstrate that D. sechellia has a reversed preference for the key ligands of these macroglomeruli, especially at high concentrations. Whereas D. melanogaster was repelled by high concentrations of these odors, D. sechellia was highly attracted. This was the case for odors presented singly, but more notably for blends thereof. Our study indicates
that relatively simple changes, such as a shift in sensillar abundance, and concordant shifts in glomerular size, can distort
the resulting olfactory code, and can lead to saltatory shifts in odor preference. D. sechellia has exploited this to align its olfactory preference with its ecological niche. 相似文献
525.
Natalia Broqvist Sture Hogmark Anna Medvedeva Staffan Gunnarsson 《Journal of Manufacturing Processes》2012,14(3):195-198
Maintaining a reasonably low cutting tool wear when producing forming tools is a general challenge in the development of new forming tool materials. The tool life of a hot forming tool steel (H13) has been significantly improved by reducing its Si-content from 1.0 to 0.06 wt.%. However, this modified H13 (MH13) also displays a reduced cutting tool life due to higher cutting forces and a stronger tendency to form built up layers (BUE) on the cutting edge. This paper explains why.Gleeble tests of MH13 revealed a significantly higher flow stress in the 820–900 °C temperature interval in MH13 compared to H13. Thermo-Calc simulations showed that when reducing the Si-content from 1.0 to 0.06 wt.% the initial temperature for ferrite-to-austenite transformation (A1) was reduced from 900 °C to 820 °C. Knowing that austenite has totally different mechanical and thermal properties than ferrite, the difference in A1 between the two steels explains the higher cutting forces and higher tendency for BUE-formation. The conclusion is that the difference in machinability between H13 and MH13 is primarily related to their difference in A1.An attempt was also made to find a new tool material composition that can combine the wear resistance of MH13 and the good machinability of H13. Thermo-Calc simulations were performed with slightly modified alloying content without changing its properties as a good forming tool material, with the aim to increase A1. For instance, reducing the Mn content from 0.5 to 0.05 wt.% proved to increase A1 from 820 to 850 °C. 相似文献
526.
Screening ecological risk assessment of persistent organic pollutants in Mediterranean sea sediments 总被引:5,自引:0,他引:5
A screening ecological risk assessment (ERA) was conducted for the first time in the Mediterranean basin in order to assess the toxicity posed to the benthic community by PCBs, DDTs and HCB in marine sediments. The characterization of the exposure was conducted by means of an extensive literature survey, generating a database with more than 2000 samples. The effects were assessed by the adoption of guidelines previously developed in the literature, because ecotoxicological information about persistent organic pollutants (POPs) in the Mediterranean sediments was lacking. Existing sediment quality guidelines (SQGs) for the target pollutants were compiled and consensus values were calculated for three different categories of toxicity, namely threshold effect concentration (TEC), probable effect concentration (PEC) and extreme effect concentration (EEC). The combination of exposure and effects characterization enabled the identification of some areas of concern in the vicinity of industrial and urban locations and in the mouths of the main Mediterranean rivers. Beyond the Mediterranean continental shelf, the level of toxicity for the benthic community was generally low. The evaluation of the toxicity induced by the mixture of the target pollutants spotted the importance of DDT contamination in the Mediterranean sediments, despite the fact that main inputs to the sea have been significantly reduced during the last decades. 相似文献
527.
Georg Philipp Mueller Anna M. Hersperger 《Journal of Environmental Planning and Management》2015,58(11):2056-2081
Evaluation in spatial planning aims to raise effectiveness of plans as well as efficiency in planning processes. Given that research regarding evaluation of performance and especially plan implementation is sparse, this study presents a minimal set of indicators for a task-sheet based performance evaluation approach for Swiss cantonal comprehensive plans. Thematic task-sheets are a promising characteristic of cantonal comprehensive plans. They translate the comprehensive planning strategy into concrete evaluable tasks. The presented indicators allow assessing procedural efficiency of coordination and implementation of planning tasks (performance). We argue that if task-sheets comply with certain plan quality characteristics, a task-sheet based performance evaluation approach can support the effectiveness of plans and promote the objectives of the planning strategy. We point out plan content and characteristics necessary for effective execution of our approach. As a result, our findings can serve as a framework for designing evaluation processes for comprehensive planning documents beyond Switzerland. 相似文献
528.
Epidemiological studies typically focus on single-parasite systems, although most hosts harbor multiple parasite species; thus, the potential impacts of co-infection on disease dynamics are only beginning to be recognized. Interactions between macroparasites, such as gastrointestinal nematodes, and microparasites causing diseases like TB, AIDS, and malaria are particularly interesting because co-infection may favor transmission and progression of these important diseases. Here we present evidence for strong interactions between gastrointestinal worms and bovine tuberculosis (TB) in free-ranging African buffalo (Syncerus caffer). TB and worms are negatively associated at the population, among-herd, and within-herd scales, and this association is not solely the result of demographic heterogeneities in infection. Combining data from 1362 buffalo with simple mechanistic models, we find that both accelerated mortality of co-infected individuals and TB transmission heterogeneity caused by trade-offs in immunity to the two types of parasites likely contribute to observed infection patterns. This study is one of the first to examine the relevance of within-host immunological trade-offs for understanding parasite distribution patterns in natural populations. 相似文献
529.
Anna Wramneby Benjamin Smith Snke Zaehle Martin T. Sykes 《Ecological modelling》2008,216(3-4):277-290
Dynamic vegetation models are useful tools for analysing terrestrial ecosystem processes and their interactions with climate through variations in carbon and water exchange. Long-term changes in structure and composition (vegetation dynamics) caused by altered competitive strength between plant functional types (PFTs) are attracting increasing attention as controls on ecosystem functioning and potential feedbacks to climate. Imperfect process knowledge and limited observational data restrict the possibility to parameterise these processes adequately and potentially contribute to uncertainty in model results. This study addresses uncertainty among parameters scaling vegetation dynamic processes in a process-based ecosystem model, LPJ-GUESS, designed for regional-scale studies, with the objective to assess the extent to which this uncertainty propagates to additional uncertainty in the tree community structure (in terms of the tree functional types present and their relative abundance) and thus to ecosystem functioning (carbon storage and fluxes). The results clearly indicate that the uncertainties in parameterisation can lead to a shift in competitive balance, most strikingly among deciduous tree PFTs, with dominance of either shade-tolerant or shade-intolerant PFTs being possible, depending on the choice of plausible parameter values. Despite this uncertainty, our results indicate that the resulting effect on ecosystem functioning is low. Since the vegetation dynamics in LPJ-GUESS are representative for the more complex Earth system models now being applied within ecosystem and climate research, we assume that our findings will be of general relevance. We suggest that, in terms of carbon storage and fluxes, the heavier parameterisation requirement of the processes involved does not widen the overall uncertainty in model predictions. 相似文献
530.
Behavioural research on domestic pigs has included parent–offspring conflict, sibling competition, and the use of signals
which influence resource allocation. In this paper, we review key sow–piglet behavioural studies and discuss their relevance
to resource allocation theory. Sibling competition begins in the uterus and continues after birth, as piglets compete directly
for access to the sow’s teats. This competition is made more severe by a unique dentition, which newborn piglets use to lacerate
the faces of siblings during teat disputes. Competition often leads to the death of some littermates, especially those of
low birth weight. Piglets also compete indirectly for milk, apparently by stimulating milk production at the teats that they
habitually use at the expense of milk production by other teats. The complex nursing behavior of the sow appears designed
to prevent the more vigorous piglets from monopolizing the milk. Sows give vocal signals which both attract piglets to suckle
and synchronize their behavior during nursing episodes. Piglets give loud vocal signals when separated from the sow; calls
which vary in intensity and appear to be honest signals of need. Udder massage by piglets may also serve as an honest signal
of need. Parent–offspring conflict has been demonstrated experimentally in pigs. Specifically, when given the opportunity
to control contact with their piglets, sows nurse less frequently, provide less milk, and lose less weight during lactation
than sows that cannot control their level of contact. Because of this interesting natural history and because they are so
amenable to experimentation, domestic pigs provide a rich system for testing ideas drawn from resource allocation theory.
This contribution is part of the special issue “Sibling competition and cooperation in mammals” (guest editors: Robyn Hudson
and Fritz Trillmich). 相似文献