Wikipedia:Reference desk/Archives/Science/2014 February 9

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February 9

why does parkinson is more common among..

Hey! Why does parkinson is more common among european and "devloped coontry's than in india, africa,asia etc. ? Thanks i advance — Preceding unsigned comment added by 207.81.253.160 (talk) 07:33, 9 February 2014 (UTC)

What would this have to do with Science? Maybe Humanities would be a better desk. -- Jack of Oz ^{[pleasantries]} 07:40, 9 February 2014 (UTC)

I think the OP means "Parkinson's Disease" and according to our article Parkinson's Disease#Epidemiology it has not been proven to be more prevalent among the groups supposed by the OP.--William Thweatt ^TalkContribs 07:44, 9 February 2014 (UTC)

And even if it was, we wouldn't be able to explain why, since the great majority of cases are "idiopathic" -- a fancy way of saying that the cause is not know. Looie496 (talk) 20:54, 9 February 2014 (UTC)

Another possibility is since Parkinson's affects older people more so than younger ones, countries with older populations will have a higher overall prevalence. 105.236.146.239 (talk) 09:56, 9 February 2014 (UTC)

• Yes, Parkinson's (which is really several similar syndromes) tends to develop in older people. In nations with lower life-expectancies people tend to die from infections, parasites, accidents, violence, hunger, and sheer exhaustion from a life of manual labor. They don't get old or sedentary enough to suffer metabolic, immune and regulatory disfunctions related to aging such as type II diabetes, Parkinsons, Alzheimer's and cancer. Forgive me, since I have no idea what single article of ours addresses this. μηδείς (talk) 21:23, 9 February 2014 (UTC)

The article is aging-associated diseases. It does point out that, globally, 66% die of age-related causes and states "In industrialized nations, the proportion is much higher, reaching 90%". --Cookatoo.ergo.ZooM (talk) 21:59, 9 February 2014 (UTC)

Thanks! μηδείς (talk) 22:03, 9 February 2014 (UTC)

To clarify a little what's already been said, because everyone dies of *something*, as you eliminate the causes of death that happen earlier in life, the percentage of people who die of things that take longer to develop (degenerative diseases like Parkinson's, some cancers, Alzheimer's, etc) must increase. Hence, it's inevitable that the better we get at treating things like infectious diseases, the more crash-resistant our cars become, the more people give up smoking, etc - the more people are going to die of Parkinson's, Alzheimer's, etc. If we find either a preventative or a cure for Parkinson's, then the percentage of Alzheimer's, cancer, etc will suddenly increase because all of those people who would have died of Parkinson's will now live to get one of these other conditions. The better medicine and accident prevention gets, the closer we edge towards something as unlikely as "Being struck by lightning" as the single largest cause of death! SteveBaker (talk) 17:14, 10 February 2014 (UTC)

Pierson's Puppeteers have come so close to being immortal, their main fears are supernovae and furniture with sharp edges. μηδείς (talk) 17:44, 10 February 2014 (UTC)

A reasonable comparison can be found at Feral cat#Life span and survival. The more dangerous or "wild" the conditions are, the shorter the lifespan is likely to be. Being safe and protected in "tame" circumstances tends to lead to a longer lifespan and a greater likelihood of dying from various "old-timers'" diseases such as Parkinson's. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:12, 10 February 2014 (UTC)

The effects of various environmental toxins can't be excluded, either. Parkinsonism happens when for some reason, the "dark matter" (substantia nigra) of certain parts of the brain dies off. The pesticide rotenone, widely used because it has a fairly low mammalian toxicity but kills insects rapidly in low doses, has been connected with the onset of parkinsonism in the laboratory. Other chemicals may have similar effects (the most notable example was an undesired byproduct in a "designer drug" synthesized to have opiate-like effects on the user... several abusers of the designer drug came down with irreversible Parkinsonism, one of whom only recovered to some extent after stem-cell therapy). loupgarous (talk) 16:42, 13 February 2014 (UTC)

You're thinking MPTP. Wnt (talk) 13:44, 17 February 2014 (UTC)

NATURE OF GLASS (and condensation)

Have u ever noticed your car glass(window) during winter,when there is a dew you see the moisture on ur car.when u get in to the car u will find the moisture on the same window glass but inside.i want to know what is the nature of glass?is glass behaves like a cloth?how can we see moisture inside the car glass(window) even its close? — Preceding unsigned comment added by Aamirsayeed1410 (talk • contribs) 08:00, 9 February 2014 (UTC)

The moisture you notice on the inside is not the same moisture from the outside that has somehow traveled through the glass. The moisture is caused by condensation. In short, warm air can hold more moisture (water vapor) than cold air. When warm air comes into contact with the cold glass, the water vapor in the warm air is deposited as liquid water on the glass. When you get into the car, you warm up the inside and your breath introduces more water vapor to the interior which condenses on the inside of the glass.--William Thweatt ^TalkContribs 08:16, 9 February 2014 (UTC)

Also, if you exited your vehicle and closed the doors/windows, you trapped air inside. If the temperature cools outside, making the glass colder than when you closed up the vehicle, the water vapor from the warmer air inside the car will be deposited on the inside of the glass as condensation.--William Thweatt ^TalkContribs 08:21, 9 February 2014 (UTC)

How does one excite a car ? Does this involve grabbing hold of it's dipstick and promising it a Kwiky Lube ? StuRat (talk) 18:38, 10 February 2014 (UTC)

So to clear internal condensation in order to drive, is it better to blow hot or cold air at the windscreen? --86.12.139.50 (talk) 13:11, 10 February 2014 (UTC)

From extensive personal experience/experimentation, hot, because the warmer the air is, the more water it takes up.

However, although this will clear the windscreen most quickly (and will keep it clear while the air continues to blow), if this warm and now moister air remains in the car it will simply cool down and redeposit the water as condensation again. My strategy is, once the screen is clear, to lower the side windows for a while during the drive, allowing cooler but hopefully dryer external air to replace the internal air with its moisture load. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 14:39, 10 February 2014 (UTC)

And if you do smell that sweet smell, get it fixed ASAP because it's not good for your health! SteveBaker (talk) 21:51, 10 February 2014 (UTC)

If your car has air-conditioning - then turning on the A/C (with the heat turned to whatever level is comfortable - and the air-flow set to "recirculate") will rapidly dry out the air inside the car - thereby removing the source of the condensation while keeping the temperature comfortable at whatever level you like. SteveBaker (talk) 17:01, 10 February 2014 (UTC)

I have to disagree on using the recirculate setting (also sometimes labelled something like "MAX A/C"). The most common cause of condensation on the inside of the windows for me is when there is cold, dry air outside, but I am inside, and my breathing and maybe wet hair from showering makes it humid in there. Therefore, I want to vent the moist air from inside and replace it with dry air from outside.

However, on a moist summer day, your recirculate option might be the best you could do, as there is no dry air to be had anywhere, so you must rely on the A/C removing water for you. (BTW, where does that condensate water go, is there a drain that dumps it onto the ground ?) StuRat (talk) 18:23, 10 February 2014 (UTC)

Yes, there is a drain. In the cars where I've dealt with it the evaporator and it's housing are above the passenger side footwell, right by the recirculator input. Condensation drips from the evaporator fins into the housing, then goes out a drain. It can also freeze to the fins on humid days if the car doesn't have a regulator to keep them from getting too cold. I have never tried running A/C in winter weather, but I would expect the sub-freezing temperature air flowing over the fins would cause the moisture in the air to be converted to ice which would freeze up the evaporator and insulate it. When that happens, the moisture stops being pulled from the air as quickly because the ice works as insulation. Katie R (talk) 20:27, 10 February 2014 (UTC)

When I first came to the US, I'd never owned an airconditioned car before - and when I saw a puddle of water on the road under the rental car on a very hot, humid day - I assumed it was a leaky radiator or something...that wasn't one of my best days!  :-) SteveBaker (talk) 21:51, 10 February 2014 (UTC)

BTW, if there is moisture on the inside of the car windows, right by the vents, soon after starting, that can be a sign of a leaky heater core. A sweet smell from the coolant is another sign. StuRat (talk) 18:29, 10 February 2014 (UTC)

Mass-killer floods

Looking at the floodplain article made me wonder: besides the 1931 Yellow River flood, do we have any articles about floods that themselves killed tons of people, e.g. the death toll was recorded as being hundreds of thousands, or more? I'm talking about the high water itself, not the flow (i.e. ruling out a flash flood that sweeps people away), or famine from being unable to grow crops in flooded fields, or illness resulting from all the refugees being packed together on high ground. I get the impression that most high-death-toll floods kill primarily with famines and illness, and the 1931 situation with hundreds of thousands of drownings would seem to be a lot rarer. Nyttend (talk) 21:53, 9 February 2014 (UTC)

Naturally we have a relevant article, list of deadliest floods. Looie496 (talk) 22:14, 9 February 2014 (UTC)