Word: specimen
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
...trying to date some fossil-laden sediment from the ocean floor. The standard method for determining the age of fossils is the so-called carbon 14 clock, which is based on the ratio of ordinary carbon atoms to atoms of the radioactive isotope carbon 14 found in the specimen. The carbon 14 atoms decay at a known rate and are not replenished after the creature dies; thus the proportion of ordinary carbon to carbon 14 slowly increases. But the carbon clock only works up to about 50,000 years after the death of the organism. After that time, almost...
...tests required only a tiny sampling of material and could be completed in a few hours. There is one serious hitch, he reports in Earth and Planetary Science Letters. Because the rate at which amino acids change their configuration varies significantly with heat, the temperature history of the specimen must be taken into account. Still, if an object has been sheltered in a cave or buried in the ocean floor, that should not be a great problem: the fossil is not likely to have undergone any great temperature variations that would upset the age calculations...
Before the first moon walk ended, scientists in Houston were surprised to hear that the multitude of rocks gathered by the astronauts apparently included few crystalline, or heat-formed specimens; that cast doubt on the theory that the Descartes area's Cayley Plains were once the site of volcanic flows. The day's prize find was made by the Houston scientists themselves. With the TV finally on after a second antenna had been aligned with earth, they could direct Duke's attention to a large, football-sized rock that glittered with imbedded black glass fragments...
Well he smaller than I had expected. At least, he's not the brawny specimen of British manhood he appears or film. Rather thin and well-dressed, soft spoken and polite. A mild joker in a veddy British way. "I'm an absolute tea-fiend. Get me some immediately, or else I shall have to inject it into my veins." (Take that damn foreigner down to Harlem.) A refined version of the feline eyes, two-coloured hair, the endearingly bumpy nose projected on the movie-screen. The Oxford accent, my dear, of course unmistakable: but not an affected one. Rather...
...some handwriting authorities that the autobiography was legitimate. The government answer: Irving himself. The indictments claim that Irving modeled his forgeries on magazine photographs showing lines from a handwritten Hughes letter. During a recent long session with federal authorities, Irving astonished the prosecutors by dashing off a near-perfect specimen of Hughes' handwriting...