17,895 research outputs found
Coronal Implosion and Particle Acceleration in the Wake of a Filament Eruption
We study the evolution of a group of TRACE 195 A coronal loops overlying a
reverse S-shaped filament on 2001 June 15. These loops were initially pushed
upward with the filament ascending and kinking slowly, but as soon as the
filament rose explosively, they began to contract at a speed of ~100 km/s, and
sustained for at least 12 min, presumably due to the reduced magnetic pressure
underneath with the filament escaping. Despite the contraction following the
expansion, the loops of interest remained largely intact during the filament
eruption, rather than formed via reconnection. These contracting loops
naturally formed a shrinking trap, in which hot electrons of several keV, in an
order of magnitude estimation, can be accelerated to nonthermal energies. A
single hard X-ray burst, with no corresponding rise in GOES soft X-ray flux,
was recorded by the Hard X-ray Telescope (HXT) on board Yohkoh, when the
contracting loops expectedly approached the post-flare arcade originating from
the filament eruption. HXT images reveal a coronal source distinctly above the
top of the soft X-ray arcade by ~15". The injecting electron population for the
coronal source (thin target) is hardening by ~1.5 powers relative to the
footpoint emission (thick target), which is consistent with electron trapping
in the weak diffusion limit. Although we can not rule out additional
reconnection, observational evidences suggest that the shrinking coronal trap
may play a significant role in the observed nonthermal hard X-ray emission
during the flare decay phase.Comment: accepted to ApJ
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'BioNessie(G) - a grid enabled biochemical networks simulation environment
The simulation of biochemical networks provides insight and
understanding about the underlying biochemical processes and pathways
used by cells and organisms. BioNessie is a biochemical network simulator
which has been developed at the University of Glasgow. This paper
describes the simulator and focuses in particular on how it has been
extended to benefit from a wide variety of high performance compute resources
across the UK through Grid technologies to support larger scale
simulations
Modelling and optimisation of a bimorph piezoelectric cantilever beam in an energy harvesting application
Piezoelectric materials are excellent transducers in converting vibrational energy into electrical energy, and vibration-based piezoelectric generators are seen as an enabling technology for wireless sensor networks, especially in selfpowered devices. This paper proposes an alternative method for predicting the power output of a bimorph cantilever beam using a finite element method for both static and dynamic frequency analyses. Experiments are performed to validate the model and the simulation results. In addition, a novel approach is presented for optimising the structure of the bimorph cantilever beam, by which the power output is maximised and the structural volume is minimised simultaneously. Finally, the results of the optimised design are presented and compared with other designs
Phylogenetic congruence between subtropical trees and their associated fungi.
Recent studies have detected phylogenetic signals in pathogen-host networks for both soil-borne and leaf-infecting fungi, suggesting that pathogenic fungi may track or coevolve with their preferred hosts. However, a phylogenetically concordant relationship between multiple hosts and multiple fungi in has rarely been investigated. Using next-generation high-throughput DNA sequencing techniques, we analyzed fungal taxa associated with diseased leaves, rotten seeds, and infected seedlings of subtropical trees. We compared the topologies of the phylogenetic trees of the soil and foliar fungi based on the internal transcribed spacer (ITS) region with the phylogeny of host tree species based on matK, rbcL, atpB, and 5.8S genes. We identified 37 foliar and 103 soil pathogenic fungi belonging to the Ascomycota and Basidiomycota phyla and detected significantly nonrandom host-fungus combinations, which clustered on both the fungus phylogeny and the host phylogeny. The explicit evidence of congruent phylogenies between tree hosts and their potential fungal pathogens suggests either diffuse coevolution among the plant-fungal interaction networks or that the distribution of fungal species tracked spatially associated hosts with phylogenetically conserved traits and habitat preferences. Phylogenetic conservatism in plant-fungal interactions within a local community promotes host and parasite specificity, which is integral to the important role of fungi in promoting species coexistence and maintaining biodiversity of forest communities
BioNessie - a grid enabled biochemical networks simulation environment
The simulation of biochemical networks provides insight and understanding about the underlying biochemical processes and pathways used by cells and organisms. BioNessie is a biochemical network simulator which has been developed at the University of Glasgow. This paper describes the simulator and focuses in particular on how it has been extended to benefit from a wide variety of high performance compute resources across the UK through Grid technologies to support larger scale simulations
Control of dissipation in superconducting films by magnetic stray fields
Hybrid superconducting/magnetic nanostructures on Si substrates have been
built with identical physical dimensions but different magnetic configurations.
By constructing arrays based on Co-dots with in-plane, out-of-plane, and vortex
state magnetic configurations, the stray fields are systematically tuned.
Dissipation in the mixed state of superconductors can be decreased (increased)
by several orders of magnitude by decreasing (increasing) the stray magnetic
fields. Furthermore, ordering of the stray fields over the entire array helps
to suppress dissipation and enhance commensurability effects increasing the
number of dissipation minima.Comment: 16 pages including 4 figures; accepted in Applied Physics Letter
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