34 research outputs found
Advances in ab-initio theory of Multiferroics. Materials and mechanisms: modelling and understanding
Within the broad class of multiferroics (compounds showing a coexistence of
magnetism and ferroelectricity), we focus on the subclass of "improper
electronic ferroelectrics", i.e. correlated materials where electronic degrees
of freedom (such as spin, charge or orbital) drive ferroelectricity. In
particular, in spin-induced ferroelectrics, there is not only a {\em
coexistence} of the two intriguing magnetic and dipolar orders; rather, there
is such an intimate link that one drives the other, suggesting a giant
magnetoelectric coupling. Via first-principles approaches based on density
functional theory, we review the microscopic mechanisms at the basis of
multiferroicity in several compounds, ranging from transition metal oxides to
organic multiferroics (MFs) to organic-inorganic hybrids (i.e. metal-organic
frameworks, MOFs)Comment: 22 pages, 9 figure
3D elemental mapping of materials and structures by laboratory scale spectroscopic X-ray tomography
Deformation-induced residual stress changes in SiC whisker-reinforced 6061 Al composites
Assessment of environments for Mars Science Laboratory entry, descent, and surface operations
The Mars Science Laboratory mission aims to land a car-sized rover on Mars’surface and operate it for at least one Mars year in order to assess whether its field area was ever capable of supporting microbial life. Here we describe the approach used to identify, characterize, and assess environmental risks to the landing and rover surface operations. Novel entry, descent, and landing approaches will be used to accurately deliver the 900-kg rover, including the ability to sense and “fly out” deviations from a best-estimate atmospheric state. A joint engineering and science team developed methods to estimate the range of potential atmospheric states at the time of arrival and to quantitatively assess the spacecraft’s performance and risk given its particular sensitivities to atmospheric conditions. Numerical models are used to calculate the atmospheric parameters, with observations used to define model cases, tune model parameters, and validate results. This joint program has resulted in a spacecraft capable of accessing, with minimal risk, the four finalist sites chosen for their scientific merit. The capability to operate the landed rover over the latitude range of candidate landing sites, and for all seasons, was verified against an analysis of surface environmental conditions described here. These results, from orbital and model data sets, also drive engineering simulations of the rover’s thermal state that are used to plan surface operations
Three-dimensional numerical investigations of new Austrian tunnelling method (NATM) twin tunnel interactions
Isolation of biochemical mutants using haploid mesophyll protoplasts of Hyoscyamus muticus
The race that stops a nation : the demand for the Melbourne Cup
This article uses the bounds testing procedure to cointegration, within an autoregressive distributed lag framework to estimate the determinants of attendance at the Melbourne Cup from its inception from 1861 to 2002. Following the literature on the demand for professional team sports, attendance is specified as a function of economic, demographic and race-specific factors. The main findings are that real income and population size are the major determinants of attendance in the long run, while in the short run the weather is the most important factor explaining attendance.<br /