3,390 research outputs found
Changing social contracts in climate-change adaptation
Risks from extreme weather events are mediated through
state, civil society and individual action
1
,
2
. We propose evolving
social contracts as a primary mechanism by which adaptation
to climate change proceeds. We use a natural experiment
of policy and social contexts of the UK and Ireland affected
by the same meteorological event and resultant flooding in
November 2009. We analyse data from policy documents and
from household surveys of 356 residents in western Ireland and
northwest England. We find significant differences between
perceptions of individual responsibility for protection across
the jurisdictions and between perceptions of future risk from
populations directly affected by flooding events. These explain
differences in stated willingness to take individual adaptive
actions when state support retrenches. We therefore show
that expectations for state protection are critical in mediating
impacts and promoting longer-term adaptation. We argue
that making social contracts explicit may smooth pathways to
effective and legitimate adaptation
A Snapshot of J. L. Synge
A brief description is given of the life and influence on relativity theory
of Professor J. L. Synge accompanied by some technical examples to illustrate
his style of work
Process chain simulation of laser powder bed fusion including heat treatment and surface hardening
Additive manufacturing (AM) has enabled the creation of geometrically complex parts for a range of industries. However, the nature of AM often requires multiple post processing techniques to be carried out to reach the desired material properties or required surface finish. This often involves heat treatment (HT), shot peening (SP) or laser shock peening (LSP). To date, hardly any process chain modelling has been carried out on manufacturing applications with AM. This investigation focuses on the finite element (FE) modelling of the complete manufacturing process chain of an AM impeller made of IN718, including the AM, HT, LSP and SP processes. The particular AM process applied to build the impeller is laser powder bed fusion (L-PBF). Each FE process is validated individually against experimental data before being applied to the impeller process chain. The validated data from each process is mapped to the next process in the chain to investigate the combined effects of manufacturing and post processing techniques. Results have shown that high tensile residual stresses induced by AM can be reduced by approximately 75% by applying HT. SP and LSP processes can further modify remaining tensile residual stresses after HT by inducing a layer of compressive stresses at the surface. In summary, this research work has demonstrated that the simulation of AM process chains using finite element techniques is sufficiently mature to support the product and process development of industrial AM components
Thermodynamics of Superstring on Near-extremal NS5 and Effective Hagedorn Behavior
We study the thermodynamical torus partition function of superstring on the
near-extremal black NS5-brane background. The exact partition function has been
computed with the helps of our previous works:[arXiv:1012.5721 [hep-th]],
[arXiv:1109.3365 [hep-th]], and naturally decomposed into two parts. The first
part is contributed from strings freely propagating in the asymptotic region,
which are identified as the superstring gas at the Hawking temperature on the
linear-dilaton background. The second part includes the contribution localized
around the `tip of cigar', which characterizes the non-extremality. Remarkably,
the latter part includes massless excitations with non-vanishing thermal
winding, which signifies that the Hagedorn-like behavior effectively appears,
even though the Hawking temperature is much lower than the Hagedorn
temperature. We also explore the high-temperature backgrounds defined by the
orbifolding along the Euclidean time direction. In those cases, the thermal
winding modes localized around the tip are found to be tachyonic, reflecting
the singularities of Euclidean backgrounds caused by orbifolding.Comment: 1+29 pages, no figure; v2 the footnote 1 is enhanced, to appear in
JHE
Factors affecting the prey preferences of jackals (Canidae)
Prey selection by carnivores can be affected by top-down and bottom-up factors. For example, large carnivores may facilitate food resources for mesocarnivores by providing
carcasses to scavenge, however mesocarnivores may hunt large prey themselves, and their diets might be affected by prey size and behaviour. We reviewed jackal diet studies and determined how the presence of large carnivores and various bottom-up factors affected jackal prey selection. We found 20 studies of black-backed jackals (Canis mesomelas) from 43 different times or places, and 13 studies of Eurasian golden jackals (Canis aureus) from 23 different times or places reporting on 3900 and 2440 dietary records (i.e. scats or stomach
contents), respectively. Black-backed jackals significantly preferred small ( 120 kg) hider species and follower species of any body size. They had a preferred and accessible prey weight range of 14-26 kg,
and a predator to ideal prey mass ratio of 1:3.1. Eurasian golden jackal significantly prefer to prey on brown hare (Lepus europaeus; 4 kg), yielding a predator to preferred prey mass ratio of 1:0.6, and a preferred and accessible prey weight range of 0 – 4 kg and 0 – 15 kg, respectively. Prey preferences of jackals differed significantly in the presence of apex predators, but it was not entirely due to carrion availability of larger prey species. Our results show that jackal diets are affected by both top-down and bottom-up factors, because apex predators as well as prey size and birthing behaviour affected prey preferences of jackals. A
better understanding of the factors affecting jackal prey preferences, as presented here, could lead to greater acceptance of mesocarnivores and reduced human-wildlife conflict
Signature of effective mass in crackling noise asymmetry
Crackling noise is a common feature in many dynamic systems [1-9], the most
familiar instance of which is the sound made by a sheet of paper when crumpled
into a ball. Although seemingly random, this noise contains fundamental
information about the properties of the system in which it occurs. One
potential source of such information lies in the asymmetric shape of noise
pulses emitted by a diverse range of noisy systems [8-12], but the cause of
this asymmetry has lacked explanation [1]. Here we show that the leftward
asymmetry observed in the Barkhausen effect [2] - the noise generated by the
jerky motion of domain walls as they interact with impurities in a soft magnet
- is a direct consequence of a magnetic domain wall's negative effective mass.
As well as providing a means of determining domain wall effective mass from a
magnet's Barkhausen noise our work suggests an inertial explanation for the
origin of avalanche asymmetries in crackling noise phenomena more generally.Comment: 13 pages, 4 figures, to appear in Nature Physic
The Influence of Orthopedic Surgery on Circulating Metabolite Levels, and their Associations with the Incidence of Postoperative Delirium
The mechanisms underlying the occurrence of postoperative delirium development are unclear and measurement of plasma metabolites may improve understanding of its causes. Participants (n = 54) matched for age and gender were sampled from an observational cohort study investigating postoperative delirium. Participants were ≥65 years without a diagnosis of dementia and presented for primary elective hip or knee arthroplasty. Plasma samples collected pre-and postoperatively were grouped as either control (n = 26, aged: 75.8 ± 5.2) or delirium (n = 28, aged: 76.2 ± 5.7). Widespread changes in plasma metabolite levels occurred following surgery. The only metabolites significantly differing between corresponding control and delirium samples were ornithine and spermine. In delirium cases, ornithine was 17.6% higher preoperatively, and spermine was 12.0% higher postoperatively. Changes were not associated with various perioperative factors. In binary logistic regression modeling, these two metabolites did not confer a significantly increased risk of delirium. These findings support the hypothesis that disturbed polyamine metabolism is an underlying factor in delirium that warrants further investigation
Design and testing of hydrophobic core/hydrophilic shell nano/micro particles for drug-eluting stent coating
In this study, we designed a novel drug-eluting coating for vascular implants consisting of a core coating of the anti-proliferative drug docetaxel (DTX) and a shell coating of the platelet glycoprotein IIb/IIIa receptor monoclonal antibody SZ-21. The core/shell structure was sprayed onto the surface of 316L stainless steel stents using a coaxial electrospray process with the aim of creating a coating that exhibited a differential release of the two drugs. The prepared stents displayed a uniform coating consisting of nano/micro particles. In vitro drug release experiments were performed, and we demonstrated that a biphasic mathematical model was capable of capturing the data, indicating that the release of the two drugs conformed to a diffusion-controlled release system. We demonstrated that our coating was capable of inhibiting the adhesion and activation of platelets, as well as the proliferation and migration of smooth muscle cells (SMCs), indicating its good biocompatibility and anti-proliferation qualities. In an in vivo porcine coronary artery model, the SZ-21/DTX drug-loaded hydrophobic core/hydrophilic shell particle coating stents were observed to promote re-endothelialization and inhibit neointimal hyperplasia. This core/shell particle-coated stent may serve as part of a new strategy for the differential release of different functional drugs to sequentially target thrombosis and in-stent restenosis during the vascular repair process and ensure rapid re-endothelialization in the field of cardiovascular disease
The Escherichia coli transcriptome mostly consists of independently regulated modules
Underlying cellular responses is a transcriptional regulatory network (TRN) that modulates gene expression. A useful description of the TRN would decompose the transcriptome into targeted effects of individual transcriptional regulators. Here, we apply unsupervised machine learning to a diverse compendium of over 250 high-quality Escherichia coli RNA-seq datasets to identify 92 statistically independent signals that modulate the expression of specific gene sets. We show that 61 of these transcriptomic signals represent the effects of currently characterized transcriptional regulators. Condition-specific activation of signals is validated by exposure of E. coli to new environmental conditions. The resulting decomposition of the transcriptome provides: a mechanistic, systems-level, network-based explanation of responses to environmental and genetic perturbations; a guide to gene and regulator function discovery; and a basis for characterizing transcriptomic differences in multiple strains. Taken together, our results show that signal summation describes the composition of a model prokaryotic transcriptome
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