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Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.

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There are 60,000 miles of blood vessels in every adult human.

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The human body's pharmacokinetics are quite varied. Our hair holds onto drugs longer than our urine, blood, or saliva. For example, alcohol can be detected in the hair for up to 90 days after it was consumed. The same is true for marijuana, cocaine, ecstasy, heroin, methamphetamine, and nicotine.

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Only 12 hours after an egg cell is fertilized by a sperm cell, the egg cell starts to divide. As it continues to divide, it moves along the fallopian tube toward the uterus at about 1 inch per day.

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According to animal studies, the typical American diet is damaging to the liver and may result in allergies, low energy, digestive problems, and a lack of ability to detoxify harmful substances.

Image of phacopidan trilobite Calymene tristani in nodule. Image of phacopidan trilobite Calymene tristani in nodule.
The first dark spot observed on Uranus. Image obtained by the HST ACS in 2006. The first dark spot observed on Uranus. Image obtained by the HST ACS in 2006.
The Secondary Mirror Does Not Create a Hole in the Image The Secondary Mirror Does Not Create a Hole in the Image
Image of an Almost-Extrasolar Planet Image of an Almost-Extrasolar Planet
The Retinal Image The Retinal Image
Video: Introduction to Heart Attacks

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