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Carbon Dating

As isotopes break down, or decay they give off radiation. Materials that decompose in this way are said to have a 'half-life'. As the quantity of material present decreases, so does the actual rate at which the material decays. The process of dating artifacts by radioactive C-14 measurement depends strictly upon this condition. Using C-14 ...

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CarbonDating
Astronomy

Jupiter's Great Red Spot - A Super Storm

The most prominent and well-known feature of the planet Jupiter is the Great Red Spot. It is not a surface feature, as the hard core of Jupiter lies at the bottom of an atmosphere that is thousands of ... Continue reading

JupiterRedSpot
Geology

Submarine Volcanoes

Submarine volcanoes and volcanic vents are common features on certain zones of the ocean floor. Some are active at the present time and, in shallow water, disclose their presence by blasting steam and ... Continue reading

SubmarineVolcanoes
Biology

The Blood-brain Barrier

In the human brain, there are approximately 400-425 miles of capillaries. Because the brain is basically a small neurochemistry factory, which makes our behavior a function of its interior chemical ... Continue reading

BloodBrain
Chemistry

What is Oxidation?

The term 'oxidation' derives from the ancient observation of rust (oxide) formation. Early chemists could determine an increase in the weight of a metal as it apparently captured something from the ... Continue reading

WhatisOxidation

Facts About Angina

FactsAboutAnginaAngina is a recurring pain or discomfort in the chest that happens when some part of the heart does not receive enough blood. It is a common symptom of coronary heart disease (CHD), which occurs when vessels that carry blood to the heart become narrowed and blocked due to atherosclerosis Angina feels like a pressing or squeezing pain, usually in the chest under the breast bone, but sometimes in the shoulders, arms, neck, jaws, or back. Angina is usually precipitated by exertion. It is usually relieved within a few minutes by resting or by taking prescribed angina medicine. Episodes of angina occur when the heart's need for oxygen increases beyond the oxygen available from the blood nourishing the heart. Physical exertion is the most common trigger for angina. Other triggers can be emotional stress, extreme cold or heat, heavy meals, alcohol, and cigarette smoking.

An episode of angina is not a heart attack. Angina pain means that some of the heart muscle in not getting enough blood temporarily--for example, during exercise, when the heart has to work harder. The pain does NOT mean that the heart muscle is suffering irreversible, permanent damage. Episodes of angina seldom cause permanent damage to heart muscle. In contrast, a heart attack occurs when the blood flow to a part of the heart is suddenly and permanently cut off. This causes permanent damage to the heart muscle. Typically, the chest pain is more severe, lasts longer, and does not go away with rest or with medicine that was previously effective. It may be accompanied by indigestion, nausea, weakness, and sweating. However, the symptoms of a heart attack are varied and may be considerably milder.

When someone has a repeating but stable pattern of angina, an episode of angina does not mean that a heart attack is about to happen. Angina means that there is underlying coronary heart disease. Patients with angina are at an increased risk of heart attack compared with those who have no symptoms of cardiovascular disease, but the episode of angina is not a signal that a heart attack is about to happen. In contrast, when the pattern of angina changes--if episodes become more frequent, last longer, or occur without exercise--the risk of heart attack in subsequent days or weeks is much higher.