Old Wives Tales | SciByte 13

Old Wives Tales | SciByte 13

This week on SciByte we throw science at a few Old Wives Tales … and see what sticks. Plus we take a look at the science that makes them true, false or somewhere in between.

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Show Notes:

Do you really catch a cold by getting cold?
  • No : The flu and the common cold are caused by viruses
  • Origins : Both the cold and the flu tend to be seasonal, which is probably why cold weather took all the ‘heat’.
  • When it is cold outside ..
    • People tend to stay inside and are more likely to spread germs to one another.
    • People are exposed to each other more in the winter than in the summer
    • School is in session, kids are around each other all day
  • There is also evidence now that viruses spread more easily through dry air.
  • Hypothermia, not just being cold, suppresses immunity
  • There are conflicting results on weather or not simple cold air exposure compromises the immune system, some experiments even show that cold air exposure stimulates the immune system
The Common Cold …. resistance is futile
  • There is still no known treatment that shortens the duration.
  • It does spontaneously resolve in 7–10 days, although symptoms can last up to three weeks
  • Average contraction rate is 2–4 times a year for an adult, and 6–12 for a child
  • Although it may produce nausea, the “stomach flu” is NOT acutally the flu virus, but gastroenteritis
  • Typically transmitted through the air by coughs or sneezes that cause aerosols containing the virus, it can also be transmitted through direct contact with bird droppings, nasal secretions, or contaminated surfaces
Speaking of cold weather and protecting yourself …
Do you really lose most of your body heat from your uncovered head?
  • Actually it depends on the circumstances.
  • Origins : US army survival manual from 1970 which strongly recommended covering the head when it is cold, since “40 to 45 percent of body heat” is lost from the head.
    • At least as recent as 2008 the US Army Survival Guide has the same warning about head protection in cold weather.
    • How did they get that? : An interpretation of the data from an experiment by the US military in the 1950s that had volunteers dressed in Arctic survival suits and exposed to bitterly cold conditions. Because the only part of their bodies left uncovered was their heads, most of their heat was lost through there.
  • It’s still a good idea to cover your head in cold weather, it does hold your brain!
    • Thermoregulation : The blood vessels in your limbs and extremities will react by constricting in the cold to preserve the heat to you ‘core’ systems. Since the brain is a core system, the blood vessels do not constrict and your body continues to try to keep your brain the same temperature.
Attention! Thermodynamics has entered the webshow
  • The fundamental modes of heat transfer are:
  • Conduction or diffusion : The transfer of energy between objects that are in physical contact
  • Convection : The transfer of energy between an object and its environment, due to fluid motion ( in this case fluid also referees to gasses, like the air)
  • Radiation : The transfer of energy to or from a body by means of the emission or absorption of electromagnetic radiation
  • Mass transfer : The transfer of energy from one location to another as a side effect of physically moving an object containing that energy
  • While you are standing in cold air the main mode of heat transfer is convection, although any physical contact you have with an object colder than you introduces conduction as well
  • In convection the amount of heat you loose per unit time is determined by the objects heat transfer coefficient the difference in the temperature and the area exposed
    • dQ / dt = –h * A ΔT
  • Conduction also relies upon material coefficients, difference in temperature and the size and shape of the object.
  • In the case of the US military experiments above, the Arctic suits provided a barrier that slowed the rate of convection from the persons body to the air; however the head had no such barrier. Therefore the head was able to conduct the body’s heat unimpeded.
But if ALL the brain is where the science happens …
If we need ‘all’ portions of our brain … what about people who have had segments of there brain removed?
  • Hemispherectomy—where half the brain is removed
    • Generally used to treat debilitating seizure disorders that do not respond to medication
    • Unbelievably, the surgery has no apparent effect on personality or memory
    • Disconnects communication between the two hemispheres, preventing the spread of seizures to the functional side of the brain.
  • Only in cases where the benefits of removing the problems caused (electrical or otherwise) by an afflicted portion of the brain outweigh the benefits that remain in the afflicted side of the brain.
Not THAT kind of hemi …
  • All hemispherectomy patients suffer at least partial hemiplegia on the side of the body opposite the removed or disabled portion, and may suffer problems with their vision as well.
  • Hemiplegia : total paralysis of the arm, leg, and trunk on the same side of the body
  • It is almost exclusively performed in children because their brains generally display more [neuroplasticity](http://en.wikipedia.org/wiki/Neuroplasticity, allowing neurons from the remaining hemisphere to take over the tasks from the lost hemisphere
  • Left Side of Brain and speech
    • It was thought at one time that if you took it after the age of two you would never talk again
    • It has been shown that while most people have problems with their speech, the younger the patient the less disability there is
Do you get cramps from swimming just after you eat?
  • NOTE : Drowning is a leading cause of accidental deaths in infants and children
  • However, the thought that a sandwich or any snack will cause you to sink like a stone is FALSE
  • Possible Origins
    • The thought that eating caused high blood flow to the stomach would cause low blood flow to limbs
    • In the 50’s and 60’s there were fewer lifeguards to it is possible that parents simply wanted to be able to relax during lunch time without worrying.
Whoever Charley is … I hate him and his horse
  • Muscle cramps are unpleasant sensations caused by muscle contractions or over shortening.
  • They can be caused my a variety of things, including muscle fatigue, low sodium, and low potassium
  • While none of the following have been conclusively proven to help, there is anecdotal evidence that most people under the grip of a cramp are willing to try.
  • alternatively tensing and relaxing the afflicted muscle, stretching, massage, heat, water, electrolytes, banana, Vitamin B, orange juice
Food, glorious food!
  • In the stomach hydrochloric acid both kills most contaminating microorganisms and begins the mechanical break down of foods
  • While there may be an increase of blood flow to the stomach wile is is ‘churned’ in the stomach that has no direct correlation to muscle contractions in your limbs
So the kids aren’t going to drown just because they ate a PB&J, what determines boy vs girl
If your belly is round it’s a girl and oval like a football it’s a boy…
  • There have been many theories throughout history about guessing the baby’s gender
  • With so many body shapes really … chances are slightly higher for a boy
  • The gender of your baby is determined by whether the fertilizing sperm has an X or a Y chromosome. An X chromosome will lead to a girl, a Y to a boy.
I’m tired after dealing with the kids at the pool, and I want to read before bed time …
Reading in dim light or sitting too close to the TV damages your eyes.
  • Dim light might make it difficult for the eyes to focus, which can cause short-term eye fatigue.
  • Challenging visual work, such as reading in insufficient light, can also lead to short-term drying of eyes because you blink less often.
  • You can’t damage your eyes by using them, unless you stare into the sun.
  • FYI : Getting too close to the set for your favorite shows won’t harm your eyes – “either from overfocusing or from radiation”
Ow! My eye!
  • Asthenopia / eye strain : When concentrating on a visually intense task, the [ciliary muscle],(http://en.wikipedia.org/wiki/Ciliary_muscle) tightens, it’s the eye muscle that helps you focus and controls blood flow to certain parts of your eye.
  • Giving the eyes a chance to focus on a distant object at least once an hour usually alleviates the problem.
  • A CRT computer monitor with a low refresh rate or a CRT television can cause similar problems because the image has a flicker. Aging CRTs also often go slightly out of focus, and this can cause eye strain. LCDs do not go out of focus and are less susceptible to visible flicker.

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