The Story of Saliva Humans secrete two kinds of saliva, stimulated and unstimulated, no more alike than most siblings. The prettier child is stimulated saliva. It comes from the parotid glands, between cheek and ear. When a plate of Erika Silletti’s spaghetti carbonara makes your mouth water, that’s stimulated saliva. It makes up 70 to 90 percent of the two to three pints of saliva each of us generates daily. We’re going to gather some now. The Salivette instructions are printed in six languages. The Salivette makes an unmistakable point: your parotid glands don’t care what you chew. Allowing you to eat is the most obvious but far from the only favor granted by saliva. Vinegar, cola, citrus juice, wine, all are in the acid range of the pH scale: from around pH 2 to 3. Sugar contributes to tooth decay only indirectly. You may be wondering, though probably not, why newborns—who have no teeth to protect—produce excessive volumes of drool. About the Author Author photo by Chris Hardy Photography
The Engines That Came In From The Cold! (The Soviet Moon Program) wait but why: Putting Time In Perspective Humans are good at a lot of things, but putting time in perspective is not one of them. It’s not our fault—the spans of time in human history, and even more so in natural history, are so vast compared to the span of our life and recent history that it’s almost impossible to get a handle on it. If the Earth formed at midnight and the present moment is the next midnight, 24 hours later, modern humans have been around since 11:59:59pm—1 second. And if human history itself spans 24 hours from one midnight to the next, 14 minutes represents the time since Christ. To try to grasp some perspective, I mapped out the history of time as a series of growing timelines—each timeline contains all the previous timelines (colors will help you see which timelines are which). All timeline lengths are exactly accurate to the amount of time they’re expressing. A note on dates: When it comes to the far-back past, most of the dates we know are the subject of ongoing debate.
Calculus II Spring 2013 sample final Brains flush toxic waste in sleep, including Alzheimer’s-linked protein, study of mice finds Scientists say this nightly self-clean by the brain provides a compelling biological reason for the restorative power of sleep. “Sleep puts the brain in another state where we clean out all the byproducts of activity during the daytime,” said study author and University of Rochester neurosurgeon Maiken Nedergaard. Those byproducts include beta-amyloid protein, clumps of which form plaques found in the brains of Alzheimer’s patients. Staying up all night could prevent the brain from getting rid of these toxins as efficiently, and explain why sleep deprivation has such strong and immediate consequences. Too little sleep causes mental fog, crankiness, and increased risks of migraine and seizure. Rats deprived of all sleep die within weeks. Although as essential and universal to the animal kingdom as air and water, sleep is a riddle that has baffled scientists and philosophers for centuries. One line of thinking was that sleep helps animals to conserve energy by forcing a period of rest.
'THE SPARK' - JACOB BARNETT INTV - BBC WORLD NEWS How Human Beings Almost Vanished From Earth In 70,000 B.C. : Krulwich Wonders... Add all of us up, all 7 billion human beings on earth, and clumped together we weigh roughly 750 billion pounds. That, says Harvard biologist E.O. Wilson, is more than 100 times the biomass of any large animal that's ever walked the Earth. Well, we've waxed. Forty? I'd never heard of this almost-blinking-out. Toba, The Supervolcano Once upon a time, says Sam, around 70,000 B.C., a volcano called Toba, on Sumatra, in Indonesia went off, blowing roughly 650 miles of vaporized rock into the air. That eruption dropped roughly six centimeters of ash — the layer can still be seen on land — over all of South Asia, the Indian Ocean, the Arabian and South China Sea. With so much ash, dust and vapor in the air, Sam Kean says it's a safe guess that Toba "dimmed the sun for six years, disrupted seasonal rains, choked off streams and scattered whole cubic miles of hot ash (imagine wading through a giant ashtray) across acres and acres of plants." So we almost vanished. But now we're back.
Graphene - the material of the future | Tomorrow Today I Saw It on the Internet, part one This is part one of a series on posts on fact checking science related articles. Read part two of this series. -- Part 3 - Part 4 The next time you log into your favorite social media site, take a moment to look at all the “amazing”, “shocking”, and “astounding” articles that your friends and family have shared. Are those things true? Why fact check? Why should you verify information before posting it? Rest assured that if you don’t fact check the information, someone else will. Misinformation also hurts your “cause”. Why would someone post information that is wrong? Well, there are several reasons. Some articles are trying to convince you to accept their viewpoint, and are willing to “bend the truth” a bit in the process. Over the next few posts, we will be looking at warning signs that you need to fact check, and some quick fact checking techniques.
The Truth About Diamonds As Babies, We Knew Morality - Emily Esfahani Smith New research supports the understanding that all people are born with a sense of good and bad. What does that say about altruism, community, and the capacity to kill one another? Several years ago, an energetic young mother, Tia, was out and about with her infant Aimee when disaster struck: a group of men, accompanied by vicious dogs, surrounded the pair, snatched up Aimee, and brutalized Tia. They left her helpless and without her daughter. Aimee was eventually rescued. But Tia was too battered to look after her. Mike, a squat and especially hairy fellow, didn't exactly look the part of a knight in shining armor. Is it correct to say that Mike's actions were "moral"? Though we share more than 95 percent of our DNA with these apes, many people think that morality is a uniquely human creation. Another idea, equally influential, is what the primatologist Frans de Waal calls veneer theory. After the babies watched these scenarios, the researchers presented each puppet to the babies.
The Schrödinger lecture 2012 - Metamaterials: new horizons in electromagnetism The Mistaken Assumptions That Changed Physics History - The Nature of Reality “Don’t assume,” they always say. Last month, Avi Loeb, an astrophysicist at Harvard, published an essay on how mistaken assumptions have delayed the progress of astronomy. In the same spirit, I wanted to find out how the course of physics has been influenced by assumptions, acknowledged or otherwise. Can lessons from the past help us be more aware of the assumptions we bring to physics today? Is it desirable—or even possible—to work without assumptions? In the years after scientists came to accept light as a wave, brilliant researchers spent untold hours chasing after the “ether,” hypothetical stuff through which light waves were thought to propagate. If Einstein resolved one roadblock, he set up another. Dice or no dice? It’s hard to imagine an astronomer dismissing observational data on the evidence of her “instinct for astronomy,” which highlights a key difference between the two fields. Hidden assumptions can also live at the heart of how we do science.
Graphene: materials in the flatland