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Hypotension

Bend to select a book from the lowest shelf, then rise quickly. Chances are, you'll feel a little lightheaded for a few seconds. The reason is a drop of blood pressure caused by the change in position. To maintain normal blood pressure levels, the heart and circulatory system must make frequent minor adjustments as we move, sit, stand, and lie ...

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Hypotension
Mathematics

How To Calculate The Volume Of A Right Cone

Cones are used every day for a variety of purposes. Perhaps the most useful application of the cone shape is as a funnel. For finding the volume, a cone is best viewed as a stack of circles, each one ... Continue reading

VolumeOfARight Cone
Engineering

Teeny Tiny Technology

What's the smallest thing you can imagine? Can you think of something extremely tiny that is also extremely strong--many times stronger than steel--and very flexible? Give up? The answer is carbon ... Continue reading

TinyTechnology
Engineering

Sundials, Ancient Clocks

The earliest and simplest form of sundial is the shadow stick. The time of day is judged by the length and position of the stick's shadow. Some nomadic peoples still use this method for timekeeping. ... Continue reading

SundialsAncientClocks
Biology

Gray Wolf - Canis lupus

Historically, most Native Americans revered gray wolves, trying to emulate their cunning and hunting abilities. However, wolves became nearly extinct in the lower 48 states in the early part of the ... Continue reading

GrayWolfCanislupus

What Is Arsenic?

WhatIsArsenicArsenic is a naturally occurring element widely distributed in the earth's crust. In the environment, arsenic is combined with oxygen, chlorine, and sulfur to form inorganic arsenic compounds. Arsenic in animals and plants combines with carbon and hydrogen to form organic arsenic compounds. Inorganic arsenic compounds are mainly used to preserve wood. Organic arsenic compounds are used as pesticides, primarily on cotton plants.

Arsenic cannot be destroyed in the environment. It can only change its form. Arsenic in air will settle to the ground or is washed out of the air by rain. Many arsenic compounds can dissolve in water. Fish and shellfish can accumulate arsenic, but the arsenic in fish is mostly in a form that is not harmful.

Breathing high levels of inorganic arsenic can give you a sore throat or irritated lungs. Ingesting high levels of inorganic arsenic can result in death. Lower levels of arsenic can cause nausea and vomiting, decreased production of red and white blood cells, abnormal heart rhythm, damage to blood vessels, and a sensation of 'pins and needles' in hands and feet. Ingesting or breathing low levels of inorganic arsenic for a long time can cause a darkening of the skin and the appearance of small 'corns' or 'warts' on the palms, soles, and torso. Skin contact with inorganic arsenic may cause redness and swelling. Organic arsenic compounds are less toxic than inorganic arsenic compounds. Exposure to high levels of some organic arsenic compounds may cause similar effects as inorganic arsenic.