Radiometric dating is a complex process complicated by

In southeast Europe from c 5400-4500/4300 (eastern and southwest Hungary), Cris (west and lowland Rumania), Kremikovci (northwest Bulgaria), and Karanovo (central and southern Bulgaria).The regional groups are differentiated by their individual painted wares, but the group of cultures is unified by non-ceramic traits such a miniature polished bone spoons, lip-plugs, rod-head figurines, and stamp seals.Uranium is weakly radioactive because all its isotopes are unstable (with half-lives of the five naturally known isotopes, uranium-233 to uranium-236 and uranium-238, varying between 159200 years and 4.5 billion years).The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99%) and uranium-235 (which has 143 neutrons).In other words, there is a relatively high likelihood that a particular mutation in a target sequence will result in antibiotic resistance.This high likelihood translates into a very rapid evolutionary process. The evolution of antibiotic resistance of any previously susceptible bacterial colony to just about any antibiotic is usually realized within a very short period of sustained antibiotic exposure.In their paper they argued that a series of insensible gradations, 1829 steps in all separated by 1% changes in visual acuity, could be crossed by an evolving population in about 350,000 generations - - or around 500,000 years.

Uranium is a chemical element with symbol U and atomic number 92.

The antibiotic age was ushered in with the accidental discovery of penicillin by Alexander Fleming (1881-1955) in 1928.

Even though it was over ten years before mass production of penicillin was achieved, a new era had arrived.

The de novo evolution of antibiotic resistance is based on the specificity of antibiotic interactions with various protein sequences within a bacterium.

Because of the specificity of such interactions, a very high ratio of mutations are able to interfere with or completely disrupt these specific interactions - and antibiotic resistance is the result.

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It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. Many contemporary uses of uranium exploit its unique nuclear properties.

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