Sentences with phrase «radioactive carbon»

In 2000, scientists proposed finding bacteria that eat a certain chemical by feeding them the compound tagged with radioactive carbon - 13.

But the atmosphere keeps making more radioactive carbon, and none of that gets into the plant after it dies.

Those changing levels of radioactive carbon could be used to estimate when individual cells in the body, and in the heart, arose.

More than 50 years later, scientists have found a way to use radioactive carbon isotopes released into the atmosphere by nuclear testing to settle a long - standing debate in neuroscience: Does the adult human brain produce new neurons?

EDITOR»S NOTE: We have received reports of using radioactive carbon - dating and microscopy proving the age the paper and the age of the

They had to calibrate the process that way because the amount of radioactive carbon in the atmosphere really does vary a bit, and they had to account for that.

study identifies 13 clouds in the molecular gas complex associated with these stars, with a total of 42610 solar masses in radioactive carbon monoxide (13CO).

closely linked and Ace use of radioactive carbon dating unswaddled exchange their spittle or laugh innocently.

The only previously known radioactive carbon isotope at the time was carbon - 11, which had a half - life of only 21 minutes (half the isotope's radioactivity will decay in that time).

The isotope has a half - life of approximately 5,600 years, which means that during this period, half the number of radioactive carbon atoms in any once - living substance will convert to nitrogen.

By measuring the ratio of radioactive carbon present in the methane contamination, however, the researchers determined that in drinking water wells near active natural gas wells, the methane was old and therefore fossil natural gas from the Marcellus Shale, rather than more freshly produced methane.

Carbon released by burning fossil fuels is diluting radioactive carbon - 14 and artificially raising the radiocarbon «age» of the atmosphere, according to a paper published today (Monday 20 July 2015) in the journal PNAS.

Hundreds of nuclear bomb detonations in the atmosphere prior to a 1963 test ban treaty doubled the amount of radioactive carbon found in the ocean.

For instance, radiocarbon dating determines the age of biological remains based on the ratio between the carbon isotopes (atoms of the same element with different numbers of neutrons) carbon - 12 and carbon - 14 it holds - this proportion changes as radioactive carbon - 14 breaks down while stable carbon - 12 does not.

Scientists have found, however, that minute levels of radioactive carbon absorbed by the barley as it grew before it was harvested to make the whisky can betray how old it is.

They sent soil samples for DNA testing, looking for matches with particular genes known to be found in microbes and fungi; they tried to stimulate microbial growth on a wide variety of substances and then count the cells produced; and they used highly sensitive radiorespiration activity assays, which involve feeding the soil microorganisms a food source which has been labelled with radioactive carbon, which can then be used to detect if the microorganisms are active.

Kim, Kawamura and colleagues find that the nebula BFS64 is associated with a molecular cloud containing 23 thousand solar masses of radioactive carbon monoxide (13CO) at a distance of 3200 pc.

radioactive carbon dating.

Charles Rubin, Kerry Sieh, Jessica Pilarczyk, and their colleagues had been reading the millennia - long histories of past tsunamis in three kinds of geologic records and determining the age of each tsunami recorded there using radioactive carbon - 14 dating.

Researchers date these phases by a combination of techniques: comparing trends in pottery design; measuring the occurrence of radioactive carbon in ashes and other debris of organic origin; and relating names occurring on tablets with those known from other sources.

Levin's recipe for smoking out Martian life was elegantly simple: Scoop up Martian dirt with the Viking arm, seal it in a chamber, add an organic compound with a trace of radioactive carbon, and wait.

To track the antibiotic's journey from water to pepper, the researchers labeled TCC with radioactive carbon (C14).

19 Plastic cards did not yet exist, so Shepherd - Barron's ATM accepted only checks laced with identifying traces of radioactive carbon - 14.

During the PET scans, participants were given a chemical — similar in structure to an antidepressant but not a high enough dose to have a pharmacological effect — labeled with a radioactive carbon.

The testing of nuclear weapons in the 1950s spewed a lot of radioactive carbon 14 into the air.

Some hit our atmosphere, creating, among other things, radioactive carbon 14.

The radioactive carbon 14 is isolated from the other atoms in a sample, making it possible to derive more accurate chronologies from much smaller archaeological or anthropological specimens

Archaeologists later found a burnt bone from an herbivore or cave bear nearby and could detect no radioactive carbon left in it — a sign that the bone was older than 50,000 years, the limit of carbon dating.

Some got single - celled algae, inoculated with radioactive carbon - 14; others received polysaccharides or proteins that contained iron.

This involved measuring the ratio of radioactive carbon (14C) to normal carbon (12C) in the nacre.

After measuring the amount of radioactive carbon in a great white's vertebrae, the researchers calculated the age of the shark.

They contained no radioactive carbon (which has almost vanished after 50,000 years).

The nutrients were laced with radioactive carbon, so if the solution was digested, a radiation monitor above the sample would detect the resulting gas.

Intriguingly, radioactive carbon was detected, but then another experiment found no evidence of organic compounds in the soil — there were no alien bodies.

The method, which has taken Spalding more than a decade to develop, hinges on a massive pulse of radioactive carbon - 14 isotopes released by nuclear explosions in the 1950s and»60s, which doubled the amount of carbon - 14 in the atmosphere.

Fossil fuels lack a type of radioactive carbon, an isotope called carbon - 14, which decays over time.

Since 1947, scientists have reckoned the ages of many old objects by measuring the amounts of radioactive carbon they contain.

These explosions produced a very large amount (relative to natural levels) of radioactive carbon - 14.

As shown in the graph below, cosmic - ray intensity (as measured by the radioactive carbon isotope C - 14) and terrestrial climate (as measured by the oxygen isotope O - 18) correlate in amazing detail over an interval of at least 3000 years (see graph below; the bottom graph is the central section, blown up to reveal detail)