Mesoscale magnetism at the grain boundaries in colossal magnetoresistive films

We report the discovery of mesoscale regions with distinctive magnetic properties in epitaxial La$_{1-x}$Sr$_{x}$MnO$_{3}$ films which exhibit tunneling-like magnetoresistance across grain boundaries. By using temperature-dependent magnetic force microscopy we observe that the mesoscale regions are formed near the grain boundaries and have a different Curie temperature (up to 20 K {\it higher}) than the grain interiors. Our images provide direct evidence for previous speculations that the grain boundaries in thin films are not magnetically and electronically sharp interfaces. The size of the mesoscale regions varies with temperature and nature of the underlying defect.Comment: 4 pages of text, 4 figure

RRS Discovery Cruise 381, 28 Aug - 03 Oct 2012. Ocean Surface Mixing, Ocean Submesoscale Interaction Study (OSMOSIS)

Cruise D381 was made in support of NERC's Ocean Surface Boundary Layer theme action programme, OSMOSIS (Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study). The ocean surface boundary layer (OSBL) deepens in response to convective, wind and surface wave forcing, which produce three-dimensional turbulence that entrains denser water, deepening the layer. The OSBL shoals in response to solar heating and to mesoscale and sub-mesoscale motions that adjust lateral buoyancy gradients into vertical stratification. Recent and ongoing work is revolutionising our view of both the deepening and shoaling processes: new processes are coming into focus that are not currently recognised in model parameterisation schemes. In OSMOSIS we have a project which integrates observations, modelling studies and parameterisation development to deliver a step change in modelling of the OSBL. The OSMOSIS overall aim is to develop new, physically based and observationally supported, parameterisations of processes that deepen and shoal the OSBL, and to implement and evaluate these parameterisations in a state-of-the-art global coupled climate model, facilitating improved weather and climate predictions. Cruise D381 was split into two legs D381A and a process study cruise D381B. D381A partly deployed the OSMOSIS mooring array and two gliders for long term observations near the Porcupine Abyssal Plain Observatory. D381B firstly completed mooring and glider deployment work begun during the preceding D381A cruise. D381B then carried out several days of targetted turbulence profiling looking at changes in turbulent energy dissipation resulting from the interation of upper ocean fluid structures such as eddies, sub-mesoscale filaments and Langmuir cells with surface wind and current shear. Finally D381B conducted two spatial surveys with the towed SeaSoar vehicle to map and diagnose the mesoscale and sub-mesoscale flows, which, unusually, are the `large scale' background in which this study sits

RRS Discovery Cruise 381, 28 Aug - 03 Oct 2012. Ocean Surface Mixing, Ocean Submesoscale Interaction Study (OSMOSIS)

Cruise D381 was made in support of NERC's Ocean Surface Boundary Layer theme action programme, OSMOSIS (Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study). The ocean surface boundary layer (OSBL) deepens in response to convective, wind and surface wave forcing, which produce three-dimensional turbulence that entrains denser water, deepening the layer. The OSBL shoals in response to solar heating and to mesoscale and sub-mesoscale motions that adjust lateral buoyancy gradients into vertical stratification. Recent and ongoing work is revolutionising our view of both the deepening and shoaling processes: new processes are coming into focus that are not currently recognised in model parameterisation schemes. In OSMOSIS we have a project which integrates observations, modelling studies and parameterisation development to deliver a step change in modelling of the OSBL. The OSMOSIS overall aim is to develop new, physically based and observationally supported, parameterisations of processes that deepen and shoal the OSBL, and to implement and evaluate these parameterisations in a state-of-the-art global coupled climate model, facilitating improved weather and climate predictions. Cruise D381 was split into two legs D381A and a process study cruise D381B. D381A partly deployed the OSMOSIS mooring array and two gliders for long term observations near the Porcupine Abyssal Plain Observatory. D381B firstly completed mooring and glider deployment work begun during the preceding D381A cruise. D381B then carried out several days of targetted turbulence profiling looking at changes in turbulent energy dissipation resulting from the interation of upper ocean fluid structures such as eddies, sub-mesoscale filaments and Langmuir cells with surface wind and current shear. Finally D381B conducted two spatial surveys with the towed SeaSoar vehicle to map and diagnose the mesoscale and sub-mesoscale flows, which, unusually, are the `large scale' background in which this study sits

Waveform Relaxation for the Computational Homogenization of Multiscale Magnetoquasistatic Problems

This paper proposes the application of the waveform relaxation method to the homogenization of multiscale magnetoquasistatic problems. In the monolithic heterogeneous multiscale method, the nonlinear macroscale problem is solved using the Newton--Raphson scheme. The resolution of many mesoscale problems per Gauss point allows to compute the homogenized constitutive law and its derivative by finite differences. In the proposed approach, the macroscale problem and the mesoscale problems are weakly coupled and solved separately using the finite element method on time intervals for several waveform relaxation iterations. The exchange of information between both problems is still carried out using the heterogeneous multiscale method. However, the partial derivatives can now be evaluated exactly by solving only one mesoscale problem per Gauss point.Comment: submitted to JC

Investigation of mesoscale meteorological phenomena as observed by geostationary satellite

Satellite imagery plus conventional synoptic observations were used to examine three mesoscale systems recently observed by the GOES-EAST satellite. The three systems are an arc cloud complex (ACC), mountain lee wave clouds and cloud streets parallel to the wind shear. Possible gravity-wave activity is apparent in all three cases. Of particular interest is the ACC because of its ability to interact with other mesoscale phenomena to produce or enhance convection

ERTS-1 Views the Great Lakes Area

ERTS-1 study of mesoscale atmospheric phenomena associated with Great Lake

Holistic mesoscale modelling of concrete – recent developments

Modelling of concrete at the mesoscale is needed in many applications, but developing a realistic mesoscale model for the analysis of concrete behaviour under general loading conditions is challenging. This paper presents an overview of the development of mesoscale modelling of concrete within a finite element framework for both quasi-static and high strain rate applications. A 2D mesoscale model incorporating random aggregates and equivalent interfacial transition zones enables examination into the effects of random aggregate structure and the sub-scale non-homogeneity within the mortar matrix on the macroscopic behaviour of concrete. In applications where multi-axial stresses and confinement effects are significant, such as under high-strain rate loading where the inertial confinement plays an important role, a realistic representation of the multi-axial stress condition becomes necessary, and this requires 3D mesoscale model. Two types of 3D mesoscale concrete model have been developed, namely a pseudo-3D mesoscale model and a full 3D mesoscale model. For the explicit representation of the fracture process, a cohesivecontact approach has been implemented, at present in a 2D mesoscale framework. Illustrative examples are given to demonstrate the performance of the mesoscale models and the results are discussed