43,530 research outputs found
Fungal community survey of Fraxinus excelior in New Zealand
The European Ash tree (Fraxinus excelsior) is widely grown throughout Europe. As a large deciduous tree species, it grows a tall, domed crown and has an attractive tree shape, so it is considered as a popular amenity tree species. European Ash is planted as an important forestry species in some European countries, and also often used for furniture making, due to its excellent wood quality. Ash species were introduced into New Zealand upon colonization in the 1800s.
Recently, ash trees throughout Europe have been observed to become damaged or die due to a severe disease known as ash dieback, caused by the fungus Chalara fraxinea. We are concerned about what will happen to the introduced ash tree in New Zealand. To our knowledge, there have been no studies on the fungi that inhabit ash trees in New Zealand. It is unknown which fungal species were present in ash at the time of the introduction to New Zealand, or which New Zealand fungi colonized ash tree after the introduction. Currently, ash dieback is not believed to be present in New Zealand.
The aim of this project was to determine the possible fungal communities on ash trees in New Zealand. We collected bark, bud and wood from three healthy ash trees, and used DNA-based methods to identify the fungi that inhabited these trees. We compared our study with a similar Swedish study to find differences and similarities in the fungi present on New Zealand and European ash trees. In total, we found 90 different fungal species. Of these species found, seven fungi could be species that came to New Zealand with the introduced ash tree. We also found one fungus that could possibly be said to have come from New Zealand. The pathogen causing ash dieback, Chalara fraxinea, was not detected
Ion-mediated RNA structural collapse: effect of spatial confinement
RNAs are negatively charged molecules residing in macromolecular crowding
cellular environments. Macromolecular confinement can influence the ion effects
in RNA folding. In this work, using the recently developed tightly bound ion
model for ion fluctuation and correlation, we investigate the confinement
effect on the ion-mediated RNA structural collapse for a simple model system.
We found that, for both Na and Mg, ion efficiencies in mediating
structural collapse/folding are significantly enhanced by the structural
confinement. Such an enhancement in the ion efficiency is attributed to the
decreased electrostatic free energy difference between the compact conformation
ensemble and the (restricted) extended conformation ensemble due to the spatial
restriction.Comment: 22 pages, 5 figure
Socially Trusted Collaborative Edge Computing in Ultra Dense Networks
Small cell base stations (SBSs) endowed with cloud-like computing
capabilities are considered as a key enabler of edge computing (EC), which
provides ultra-low latency and location-awareness for a variety of emerging
mobile applications and the Internet of Things. However, due to the limited
computation resources of an individual SBS, providing computation services of
high quality to its users faces significant challenges when it is overloaded
with an excessive amount of computation workload. In this paper, we propose
collaborative edge computing among SBSs by forming SBS coalitions to share
computation resources with each other, thereby accommodating more computation
workload in the edge system and reducing reliance on the remote cloud. A novel
SBS coalition formation algorithm is developed based on the coalitional game
theory to cope with various new challenges in small-cell-based edge systems,
including the co-provisioning of radio access and computing services,
cooperation incentives, and potential security risks. To address these
challenges, the proposed method (1) allows collaboration at both the user-SBS
association stage and the SBS peer offloading stage by exploiting the ultra
dense deployment of SBSs, (2) develops a payment-based incentive mechanism that
implements proportionally fair utility division to form stable SBS coalitions,
and (3) builds a social trust network for managing security risks among SBSs
due to collaboration. Systematic simulations in practical scenarios are carried
out to evaluate the efficacy and performance of the proposed method, which
shows that tremendous edge computing performance improvement can be achieved.Comment: arXiv admin note: text overlap with arXiv:1010.4501 by other author
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