Ab initio study of the elastic behavior of MgSiO3 ilmenite at high pressure

We investigate the athermal high pressure behavior of the elastic properties of MgSiO3 ilmenite up to 30 GPa using the ab initio pseudopotential method. Our results at zero pressure are in good agreement with single-crystal elasticity measurements. The elastic anisotropy is shown to decrease slightly under compression and hence to remain substantial (25 to 20% shear wave anisotropy and 16 to 10% longitudinal wave anisotropy) over the pressure regime studied. The directions of fastest and slowest wave propagation are found to change slightly with pressure as determined by the pressure dependence of c(14) and c(25). Comparisons with the elastic behavior of other deep transition zone phases such as ringwoodite and garnet show that ilmenite is likely to be the fastest and most anisotropic mineral in this region. Large contrasts (approximate to 10%) in velocities and densities between ilmenite and garnet are suggested to be significant for the interpretation of lateral structure in the transition zone

Scouting the spectrum for interstellar travellers

Advanced civilizations capable of interstellar travel, if they exist, are likely to have advanced propulsion methods. Spaceships moving at high speeds would leave a particular signature which could be detected from Earth. We propose a search based on the properties of light reflecting from objects travelling at relativistic speeds. Based on the same principles, we also propose a simple interstellar beacon with a solar sail

Background, Global trend and Types of Mariculture

Fisheries and aquaculture are important sources for food and livelihoods for more than one billion people in the world. The waterways and oceans cover about two thirds of the surface of the earth and it forms the most underutilised natural resource when it comes to food production. The fact that aquaculture is the world’s fastest growing food production technology indicates not only that one has started to exploit this potential but also if man succeeds in using the oceans more efficiently, aquaculture can be the largest single contributor to less pressure on land

Arcology and arcosanti: towards a sustainable built environment

Does theory arcology and practice (the Arcosanti Project) respond to the overlapping challenges in the movement toward more sustainable built environments

Coyote Medicine and Biotech Culture: Mad Scientists, Jesus and Evil Aliens, and the Dangerous and Uncontrollable Power of Women

The author explores a dialogue between Native American religion and culture, Christianity, and science, for the purpose of determining some ways in which Native American religious tradition can offer a helpful perspective and corrective for some of the theological and ethical dilemmas that arise from historical interrelatedness of science and \"conquering \" Christianity. A kind of secular Christianity-of-conquest has been used as a justification for unreflected and ethically dubious choices in science. Working with Trickster stories and concepts, is it possible to engage the teachings of Jesus in new and subtle ways to make critical assessments of developments in biotechnology