These are not buns of mere steel but of some unimaginably dense substance that forms the Earth's core.
The hot, dense substance, called a quark-gluon plasma, has managed to generate intense disputes in the 15 years or so in which scientists have pursued it.
The density values suggest that Io and Europa have a rocky composition similar to that of the Moon, whereas roughly 50 percent of Ganymede and Callisto must be made of a much less dense substance, water ice being the obvious candidate.
Wireless communication within a dense substance such as soil or rock is, however, significantly more challenging than through air.
Hydrogen is the least dense substance on the planet, so in order to get enough onboard to travel 300 miles, hydrogen has to be seriously condensed.
A discontinuous layer of an electron dense substance was observed beneath the boarder between the endothelial layer and Descemet's membrane (fig 5).
Every 2 to 3 sections, 5 sections in total per implant, were sampled for the analysis, and their surfaces were stained with toluidine blue at pH 7. Tissue classification was based on morphology: new bone was a disorganized, dense substance with embedded cells colored dark purple; allograft was a dense substance with empty cell lacunae and clear cement lines colored pale purple.
The thin (2 3 μm) layer of anterior stroma beneath the treatment zone was close to normal, with rare exceptions of aggregations of electron dense substance, few irregularly located collagen fibres with small variations of their diameter (fig 9).
A solid waste byproduct of this Pb purifying process, slag is a dense substance that is more toxic than gangue and must be secured and monitored closely to avoid human exposure.
However, no previous study had to deal with the challenging situation of bone as an optically dense substance overlying a liquid as in the guinea pig cochlea in the present study.
