The ability of six-year-old children to combine perspectives of spatial layouts in their own neighbourhood was assessed. The children were asked to imagine themselves as being at a particular reference site and to decide which of two landmarks was closer to the site. From a theoretical point of view, one should not expect six-year-olds to have acquired projective and Euclidian concepts. Nevertheless, the judgements were internally consistent and tended to be veridical. This sensitiveness to relative and absolute accuracy was interpreted as a step towards a general cognitive capacity, governing the representation of spatial relations. Distances to the home were underestimated relative distances to other landmarks. Also estimations from the home tended to be more accurate than estimations from other reference sites. These results suggest that the home acts as a central reference point in children's mental representation of the environment. 相似文献
Two experiments examined whether differences in elevation of the terrain are encoded in cognitive maps of outdoor environments. In Experiment 1, two groups of subjects who had travelled a varying number of times between a set of locations made direct estimates in metres of the differences in elevation between the locations. The results showed that subjects in both groups had knowledge of elevation but those for whom the terrain was less familiar tended to exaggerate the differences. In Experiment 2, decision times were measured of responses to the question whether one location is below or above another one. Neither for subjects who were more, nor for subjects who were less familiar with the terrain, did the decision times vary with the distances between the locations, thus failing to support the hypothesis that differences in elevation are retrieved by a process of ‘mental travel’. 相似文献
Sludge from gullies, on two types of streets with different traffic intensity, was investigated using two recommended EU methods for leachability testing of waste: a two-stage batch test and an up-flow percolation test. The main purpose of this investigation was to gain more knowledge about these leaching test methods to be able to make future decisions on the general applicability of the proposed tests. A number of parameters were determined in the sludge as well as in the eluates obtained from the two leaching tests. These include pH, conductivity, dissolved organic carbon and inorganic ions as chloride ions. A number of metals as Cd, Cr, Cu, Hg, Ni and Zn, were determined by inductive coupled plasmamass spectrometry and organic compounds were screened by high performance liquid chromatography-diode array UV detection and gas chromatography-mass spectrometry. It was found that the concentrations of metals and organic compounds in the sludge were several orders of magnitudes higher than the actual eluate concentrations. For all metals the concentrations were well below the proposed limit values for non-hazardous waste included in the Council decision document 2003/33/EC. Generally, concentrations obtained in batch test were equal or higher than from percolation tests. The repeatability of the percolation and the batch test were in average 28 and 17%, respectively. 相似文献
Parasite-mediated selection may affect the evolution of cognitive abilities because parasites may influence development of
the brain, but also learning capacity. Here, we tested some predictions of this hypothesis by analyzing the relationship between
complex behaviours (feeding innovations (as a measure of behavioural flexibility) and ability to detect foreign eggs in their
nests (i.e. a measure of discriminatory ability)) and abundance of microorganisms in different species of birds. A positive
relationship would be predicted if these cognitive abilities implied a larger number of visited environments, while if these
skills favoured detection and avoidance of risky environments, a negative relationship would be the prediction. Bacterial
loads of eggshells, estimated for mesophilic and potentially pathogenic bacteria (i.e. Enterococcus, Staphylococcus and Enterobacteriaceae), were used as a surrogate of probability of contact with pathogenic bacteria. We found that bird species with higher feeding
innovation rates and rejection rates of experimental brood parasitic eggs had higher density of bacteria on their eggshells
than the average species. Since the analysed groups of microorganisms include pathogenic bacteria, these results suggest that
both feeding innovation and ability to recognize foreign eggs are costly and highlight the importance of parasite-mediated
selection in explaining the evolution of cognitive abilities in animals. 相似文献
The potential for CO2 emission reductions through carbon capture and storage (CCS) is depending on investments that can bring the technology from the current R&D through to commercial applications. The intermediate step in this development is demonstration plants that can prove the technical, economic, social, and ecological feasibility of CCS technologies. Based on a CCS stakeholder questionnaire survey and a literature review, we critically analyse discrepancies regarding perceptions of deployment obstacles and experiences from early demonstration plants. The analysis identifies discrepancies between CCS policies versus important deployment considerations and CCS stakeholder policy demands. The discrepancy gap is emphasised by lessons from restructured, postponed, and cancelled CCS projects. To bridge this cognitive gap towards proving CCS through demonstration activities, the article highlights policy implications of establishing a broad understanding of deployment obstacles. Attention to these obstacles is important for policymakers and industry in channelling efforts to demonstrating CCS, hence validating the current focus on CCS as a key abatement potential. Under present conditions, the findings question the robustness of current CCS abatement potential estimates and deployment goals as established by policymakers and in scenarios. 相似文献
Hamilton and Zuk (Science 218:384–387, 1982) supported their influential hypothesis of parasite-mediated sexual selection based on a positive interspecific correlation
between the prevalence of blood parasites and the expression of male displays in birds. However, subsequent studies provided
mixed support for this relationship after considering several confounding factors. Here, we revisit this fundamental prediction
by refining the analyses through implementation of recent methodological advancements. First, we distinguish between prevalence
data obtained through microscopic and molecular tools, as PCR-based detection methods may be more sensitive for detecting
infection. Second, we use quantitative estimates of both acoustic and visual signals of males, in which color measurements
adopt the perspective of avian vision. Third, applying modern phylogenetic comparative approaches, we correct for phylogenetic
inertia as well as heterogeneity in sampling effort. Fourth, we distinguish between prevalence transition states, as we compare
species with and without evidence of infection and also monitor changes in parasite prevalence only in species in which blood
parasites are detected. We show that given the considerable variation among populations, the repeatability of prevalence at
the within-species level is modest. We failed to detect a strong interspecific relationship between the prevalence of blood
parasites and sexual traits. However, we found that an evolutionary increase from zero to non-zero prevalence is likely to
be accompanied by an increase in trait expression in males, but further increase from non-zero prevalence to a higher level
of infection tends to be associated with a reduced degree of trait elaboration. Our results provide some support to the Hamilton
and Zuk hypothesis, but the relationship between blood parasites and male displays varies among traits depending on degree
of infection. 相似文献
Surprisingly little is known about potential effects of ocean acidification on krill of the Northern Hemisphere as ecologically very important food web component. Sub-adult individuals of the northern Atlantic krill species Nyctiphanes couchii (caught at Austevoll near Bergen, Norway, in January 2013) were exposed in the laboratory to four different levels of pCO2 (430, 800, 1,100, and 1,700 µatm) for 5 weeks in order to assess potential changes in a set of biological response variables. Survival decreased and the frequency of moulting-related deaths increased with increasing pCO2. Survival was considerably reduced at relatively high pCO2 of 1,700 µatm and tended to be negatively affected at 1,100 µatm pCO2. However, the experimental results show no significant effects of pCO2 on inter-moult period and growth at pCO2 levels below 1,100 µatm. No differences in length measurements of the carapace and uropod were observed across pCO2 levels, indicating no effect of changing carbonate chemistry on the morphology of those calciferous parts of the exoskeleton. The results suggest that sub-adult N. couchii may not suffer dramatically from predicted near-future changes in pCO2. However, potential detrimental effects on the moulting process and associated higher mortality at 1,100 µatm pCO2 cannot be excluded. Further experiments are needed in order to investigate whether early life stages of N. couchii show a different sensitivity to elevated sea water pCO2 and whether those results are transferable to other krill species of the Northern Hemisphere. 相似文献
Contamination of coastal water is a persistent threat to ecosystems around the world. In this study, a novel model for describing the dispersion, dilution, terminal layer formation and influence area from a point source discharge into a water body is presented and compared with field measured data. The model is a Combined Integral and Particle model (CIPMO). In the initial stage, the motion, dispersion and dilution of a buoyant jet are calculated. The output from the buoyant jet model is then coupled with a Lagrangian Advection and Diffusion model describing the far-field. CIPMO ensures that both the near- and far-field processes are adequately resolved. The model either uses empirical data or collects environmental forcing data from open source hydrodynamic models with high spatial and temporal resolution. The method for coupling the near-field buoyant jet and the particle tracking model is described and the output is discussed. The model shows good results when compared with measurements from a field study.
Phylogenetic comparative studies rely on species-specific data that often contain missing values and/or differ in sample size among species. These phenomena may violate statistical assumptions about the non-random variance component in sampling effort. A major reason why this assumption is often not fulfilled is because the probability of being sampled (i.e., being captured or observed) may depend on species-specific characteristics. Here, we test this assumption by using information on within-species sample sizes and missing data from five independent comparative datasets of European birds. First, we show that the two estimates of data availability (missing values and within-species sample size) are positively correlated and are associated with research effort in general (the number of papers published). Second, we demonstrate biologically meaningful relationships between data availability and phenotypic traits. For example, population size, risk-taking, and habitat specialization independently predicted within-species sample size. The key determinants of missing data were population size and distribution range. However, data availability was not structured by phylogenetic relationships. These results indicate that the accuracy of sampling is repeatable and distributed non-randomly among species, as several species-specific attributes determined the probability of observation. Therefore, data availability seems to be a species-specific trait that can be shaped by ecology, life history, and behavior. Such relationships raise issues about non-random sampling, which requires attention in comparative studies. 相似文献
Focus is placed on substrate pre-treatment in anaerobic digestion (AD) as a means of increasing biogas yields using today's diversified substrate sources. Current pre-treatment methods to improve AD are being examined with regard to their effects on different substrate types, highlighting approaches and associated challenges in evaluating substrate pre-treatment in AD systems and its influence on the overall system of evaluation. WWTP residues represent the substrate type that is most frequently assessed in pre-treatment studies, followed by energy crops/harvesting residues, organic fraction of municipal solid waste, organic waste from food industry and manure. The pre-treatment effects are complex and generally linked to substrate characteristics and pre-treatment mechanisms. Overall, substrates containing lignin or bacterial cells appear to be the most amendable to pre-treatment for enhancing AD. Approaches used to evaluate AD enhancement in different systems is further reviewed and challenges and opportunities for improved evaluations are identified. 相似文献