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Risk factors for ischaemic stroke largely mirror the risk factors for atherosclerosis and include age, gender, family history, smoking, hypertension, hypercholesterolaemia and diabetes.An ischaemic stroke typically presents with rapid onset neurological deficit, which is determined by the area of the brain that is involved.Radioactive decay occurs at a constant rate, specific to each radioactive isotope.Since the 1950s, geologists have used radioactive elements as natural "clocks" for determining numerical ages of certain types of rocks. "Forms" means the moment an igneous rock solidifies from magma, a sedimentary rock layer is deposited, or a rock heated by metamorphism cools off.
Not only does it decay by giving off energy and matter, but it also decays at a rate that is characteristic to itself.Let's look closely at how the half-life affects an isotope. Therefore, after one half-life, you would have 5 grams of Barium-139, and 5 grams of Lanthanum-139.After another 86 minutes, half of the 5 grams of Barium-139 would decay into Lanthanum-139; you would now have 2.5 grams of Barium-139 and 7.5 grams of Lanthanum-139.After one half-life of a given radioisotope, only one half as much of the original number of atoms remains active.Another way to look at this is that if the radiation intensity is cut in half; the source will have only half as many curies as it originally had.