4,744 research outputs found
Impact of intrinsic localized modes of atomic motion on materials properties
Recent neutron and x-ray scattering measurements show intrinsic localized
modes (ILMs) in metallic uranium and ionic sodium iodide. Here, the role ILMs
play in the behavior of these materials is examined. With the thermal
activation of ILMs, thermal expansion is enhanced, made more anisotropic, and,
at a microscopic level, becomes inhomogeneous. Interstitial diffusion, ionic
conductivity, the annealing rate of radiation damage, and void growth are all
influenced by ILMs. The lattice thermal conductivity is suppressed above the
ILM activation temperature while no impact is observed in the electrical
conductivity. This complement of transport properties suggests that ILMs could
improve thermoelectric performance. Ramifications also include thermal
ratcheting, a transition from brittle to ductile fracture, and possibly a phase
transformation in uranium.Comment: 34 pages, 11 figure
Multichannel parametrization of \pi N scattering amplitudes and extraction of resonance parameters
We present results of a new multichannel partial-wave analysis for \pi N
scattering in the c.m. energy range 1080 to 2100 MeV. This work explicitly
includes \eta N and K \Lambda channels and the single pion photoproduction
channel. Resonance parameters were extracted by fitting partial-wave amplitudes
from all considered channels using a multichannel parametrization that is
consistent with S-matrix unitarity. The resonance parameters so obtained are
compared to predictions of quark models
Pacific Island food security: situation, challenges and opportunities
In recent years, there have been large and rapid increases in the prices of basic foods worldwide. Pacific island countries have not been isolated from the global food 'crisis'. This article shows that there are substantial differences in the impacts within and between Pacific island countries. To be effective and not counterproductive, policy and donor responses need to be tailored accordingly. This article recommends a combination of measures directed at mitigating the threats and empowering rural people to take advantage of the opportunities
Gordon Valentine Manley and his contribution to the study of climate change: a review of his life and work
British climatologist and geographer, Gordon Manley (1902–1980), is perhaps best known for his pioneering work on climate variability in the UK, for establishing the Central England Temperature series and, for his pivotal role in demonstrating the powerful relationship between climate, weather, and culture in post-World War II Britain. Yet Manley made many contributions, both professional and popular, to climate change debates in the twentieth century, where climate change is broadly understood to be changes over a range of temporal and spatial scales rather than anthropogenic warming per se. This review first establishes how Manley's work, including that on snow and ice, was influenced by key figures in debates over climatic amelioration around the North Atlantic between 1920s and 1950s. His research exploring historical climate variability in the UK using documentary sources is then discussed. His perspectives on the relationship between climate changes and cultural history are reviewed, paying particular attention to his interpretation of this relationship as it played out in the UK. Throughout, the review aims to show Manley to be a fieldworker and an empiricist and reveals how he remained committed to rigorous scientific investigation despite changing trends within his academic discipline
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