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Shape and efficiency of wood ant foraging networks 总被引:2,自引:1,他引:1
Jerome Buhl Kerri Hicks Esther R. Miller Sophie Persey Ola Alinvi David J. T. Sumpter 《Behavioral ecology and sociobiology》2009,63(3):451-460
We measured the shape of the foraging trail networks of 11 colonies of the wood ant Formica aquilonia (Formica rufa group). We characterized these networks in terms of their degree of branching and the angles between branches, as well as
in terms of their efficiency. The measured networks were compared with idealized model networks built to optimize one of two
components of efficiency, total length (i.e., total amount of trail) and route factor (i.e., average distance between nest
and foraging site). The analysis shows that the networks built by the ants obtain a compromise between the two modes of efficiency.
These results are largely independent of the size of the network or colony size. The ants’ efficiency is comparable to that
of networks built by humans but achieved without the benefit of centralized control. 相似文献
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Jianyong Wu Paula Rees Sara Storrer Kerri Alderisio Sarah Dorner 《Journal of the American Water Resources Association》2009,45(1):35-44
Abstract: Escherichia coli was used as a bacterial tracer for the development, calibration, and validation of a watershed scale fate and transport model to be extended to a suite of reference pathogens (Cryptosporidium, Giardia, Campylobacter, E. coli O157:H7). E. coli densities in water and sediments from the Blackstone River Watershed, Massachusetts, were measured at three sites for a total of five wet weather events and three dry weather events covering three seasons. The confirmed E. coli strains were identified by ribotyping for tracking the sources of E. coli and for determining the association of downstream E. coli isolates with isolates from upstream sediments. A large number of downstream samples were associated with upstream sediment sources of E. coli. E. coli densities ranged from 71 to 6,401 MPN/100 ml in water samples and from 2 to 335 MPN/g in sediments. Pearson correlation analysis revealed significant correlations between E. coli and total coliforms in water (r = 0.777, p < 0.01) and sediments (r = 0.728, p < 0.01). In addition, E. coli concentrations in water were weakly correlated with sediment particle size and sediment concentrations (r = 0.298, p < 0.01). A hydrologic model, WATFLOOD/SPL9, was used to predict the temporal and spatial variation of E. coli in the Blackstone River. The rapid rise of stream E. coli densities was more accurately predicted by the model with the inclusion of sediment resuspension, thus demonstrating the importance of the process. 相似文献
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Nancy L. Douglas Kerri M. Mullen Stephanie C. Talmage C. Drew Harvell 《Marine Biology》2007,150(6):1137-1144
Chitinases are involved in defense against chitinaceous pathogens in both invertebrates and vertebrates. This study investigated
whether sea fan corals, Gorgonia ventalina (Linnaeus) collected from the Florida Keys between the summer of 2002 and the summer of 2005 contain chitinases, and whether
these enzymes could serve an analogous protective role against the fungal pathogen, Aspergillus sydowii (Thom et Church). Crude extracts of healthy sea fans contained detectible levels of exochitinase activity in an in vitro
microplate assay using fluorogenic substrates. The exochitinase levels decreased upon injury, agitation, or manipulation of
the tissue. A concurrent, transient increase of exochitinase in the surrounding water suggests that sea fans release chitinases
as a response to these stresses. By contrast, endochitinase was detected in only 2 of 15 sea fans (13%), suggesting a high
degree of variation for this enzyme. Sea fan chitinase-containing seawater and anion exchange chromatography fractions were
both active against A. sydowii in an absorbance-based antifungal assay. The presence of chitinases in sea fan extracts, their release into the surrounding
water upon stress, and their activity against A. sydowii suggests that further study of these enzymes in coral stress responses is warranted. 相似文献
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Thomas M. Crea Kerri Evans Robert G. Hasson III Sarah Neville Kelsey Werner Elizabeth Wanjiku Nobert Okumu Gregory St. Arnold Eric Velandria Daniela Bruni 《Disasters》2023,47(1):99-113
Children in refugee camps, and particularly those with disabilities, face unique challenges in accessing education and are at high risk of being marginalised. Best practices suggest that main-streaming is the optimal strategy for serving students with disabilities. This study examines the extent to which mainstreaming in a refugee camp helps to promote children's prosocial behaviours, taking into account their emotional and behavioural problems. In Kakuma Refugee Camp, Kenya, researchers collected data from the parents of children currently enrolled in special needs education centres (n=65) and from those formerly enrolled at these facilities who transitioned to mainstream classrooms (n=81). Children in mainstream schools functioned better in terms of prosocial behaviours, but this relationship disappeared when factoring in children's emotional and behavioural difficulties. In the context of a refugee camp, mainstreaming alone is not likely to help children's psychosocial and educational functioning, which requires dedicated supports, appropriate facilities and infrastructure, and a dual focus on disability-specific and disability-inclusive initiatives. 相似文献
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Esther Carmen Ioan Fazey Helen Ross Melissa Bedinger Fiona M. Smith Katrin Prager Kerri McClymont David Morrison 《Ambio》2022,51(6):1371
Social capital is considered important for resilience across social levels, including communities, yet insights are scattered across disciplines. This meta-synthesis of 187 studies examines conceptual and empirical understandings of how social capital relates to resilience, identifying implications for community resilience and climate change practice. Different conceptualisations are highlighted, yet also limited focus on underlying dimensions of social capital and proactive types of resilience for engaging with the complex climate change challenge. Empirical insights show that structural and socio-cultural aspects of social capital, multiple other factors and formal actors are all important for shaping the role of social capital for guiding resilience outcomes. Thus, finding ways to work with these different elements is important. Greater attention on how and why outcomes emerge, interactions between factors, approaches of formal actors and different socio-cultural dimensions will advance understandings about how to nurture social capital for resilience in the context of climate change. 相似文献
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We examined constraints on soil CO2 respiration in natural oak woodlands, and adjacent vineyards that were converted approximately 30 yr ago from oak woodlands, in the Oakville Region of Napa Valley, California. All sites were located on the same soil type, a Bale (variant) gravelly loam (fine-loamy, mixed, superactive, thermic Cumulic Ultic Haploxeroll) and dominated by C3 vegetation. Seasonal soil CO2 efflux was greatest at the oak woodland sites, although during the summer drought the rates of soil CO2 efflux measured from oak sites were generally similar to those measured from the vineyards. Soil profile CO2 concentrations at the oak woodland sites were lower below 15 cm despite higher CO2 efflux rates. Soil gas diffusion coefficients for oak sites were larger than for vineyard sites, and this indicated that the apparent discrepancy in soil profile carbon dioxide concentration ([CO2]) may be caused by a diffusion limitation. Soil profile [CO2] and delta13C values showed substantial temporal changes over the course of a year. Vineyard soil CO2 was more depleted in 13CO2 below 25 cm in the soil profile during the active growing season as indicated by more negative delta13C ratios. This result indicated that different C sources were being oxidized in vineyard soils. Annual C losses were less from vineyard soils (7.02 +/- 0.58 Mg C ha(-1) yr(-1)) as compared to oak soils (15.67 +/- 1.44 Mg C ha(-1) yr(-1)), and both were comparable to losses reported in previous investigations. 相似文献