Wikipedia:Reference desk/Archives/Science/2012 March 31

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March 31

Pupil Dilation

Is it true that one of the causes of the pupil's dilation is when the subject is romantically interested in another person with whom they are in contact?186.28.49.19 (talk) 00:49, 31 March 2012 (UTC)

See pupil dilation. The first paragraph says it "may indicate interest in the subject of attention or indicate sexual stimulation", and a scientific reference is provided. Relatedly, some cultures have believed that dilated pupils make a person more attractive, perhaps because it creates the impression of increased interest, see Belladonna_(plant)#Cosmetics. Indeed, Belladonna is so named because it was used to make a lady look beautiful. SemanticMantis (talk) 03:43, 31 March 2012 (UTC)

Back pain is common because we sleep on mattresses?

My personal experience and some thinking about this issue suggests that we're better off sleeping on the floor. When I bought a new mattress, I was adviced to get one of soft to medium firmness, these are supposed to be good for the back. I weigh 60 kg, and then a soft to medium mattress should give the best support. Firm mattresses are recommended for people over 100 kg, and super firm mattresses for people who are heavier than 160 kg. I ended up choosing one of medium firmness.

However, after several weeks sleeping on this expensive mattress, I got horrible back pains. I never had back pain before. Since my old mattress was a lot firmer than the new mattress, I was convinced that my back needs to rest on a firm mattress. I decided to sleep on my mattress back and the back pain was completely gone in a matter of a week.

Then, I still needed to buy a good mattress that would fit in my new bed, so I went back to the dealer, explaining the problem. A new super firm mattress was ordered. Unfortunately for me, these are also much more expensive than the medium firmness mattresses. The end result is that I now sleep on a super firm mattress, which also costs a super amount of money :( .

During the time I had back pain while sleeping on the medium matress, I noted the following. If you sleep on a hard mattress or lay on the floor, you can move your hand beneath the lower part of your back. But on a mattress of medium firmness, what happens is that this space is filled up by the mattress, so the mattress keeps your back in that position.

This is the only relevant difference that I noted, so it seems to me that the lower back should not be supported by the mattress. Gravity will pull your back a bit straight and that, I guess, allows the muscles in your back to relax. A medium firmness mattress will, by supporting the lower back in its naturally bent position, prevent the muscles from relaxing properly during sleep.

Now, mattresses are a recent invention, so one has to wonder if the fact that so many people complain about back pain has something to do with sleeping on mattresses. Surely, people living in the Stone Age did not suffer as much from back pain as we do today?

Now, if sleeping on super firm mattresses is indeed good for the back, then you could just as well sleep on the floor. That is only a little less comfortable, but much cheaper. And then I'm only 60 kg, if you weigh 100 kg or more, then a super firm mattress would still be way too soft.

So, should we all do away with beds and mattresses and sleep on the ground? Count Iblis (talk) 02:34, 31 March 2012 (UTC)

There is a problem with firm mattresses, though, in that they can cause pressure points. That is, the bits of flesh squeezed between your bones and the firm mattress can have too much pressure on them. This either results in constant turning, which interrupts sleep, or in damage to those areas, like bruises. It works out that lightweight people can typically tolerate a wider range of mattresses, while the obese may not have any firmness which doesn't cause one problem or another. For a nice compromise on firmness, I suggest a mattress directly on the floor, with no bed-spring underneath. The mattress can be a thin, soft one, making it inexpensive. This also avoids the occasional problem with squeaky springs. :-) Falling out of bed is also less painful, but getting up can be more of an effort.

Note that the underlying cause of back pain in humans is that we are bipedal, but with a spine designed for quadrupedal motion, which has been modified just enough to get it to barely work. Imagine a suspension bridge balanced on it's end, then shored up until it (barely) manages to stay upright. StuRat (talk) 02:43, 31 March 2012 (UTC)

About your last point, did bipedal animals like T-Rex have some special features preventing it from getting back pain that we don't have? Count Iblis (talk) 03:07, 31 March 2012 (UTC)

Yes, their spine wasn't upright like ours, but remained relatively horizontal, with a massive tail balancing against their head and torso. For birds like the ostrich, most of the spine is also horizontal, although it often turns vertical at the head. StuRat (talk) 03:14, 31 March 2012 (UTC)

From my experience, the common types of mattresses varies quite significantly from country to country. It's generally suggested that mattresses in large parts of Asia (e.g. China, India, Malaysia) are much more firm then those in countries like NZ, the UK and the US. And the construction of mattresses also varies (although there's also usually choice), e.g. springs with foam or latex support, all latex or all foam, a combination of latex and foam etc. (With various kinds of springs such as pocket springs and inner springs, foams and fibres.) There's also fancy stuff like memory foam. I don't really understand StuRat's suggestion, if you want to save money or prefer not to use a bed then fine, but if not, just choose a bed with a solid based if that's what you prefer. Also from my experience here in NZ, the recommendations when choosing a bed seem to vary from store to store and probably sales person to sales person, but weight doesn't generally seem to be a big consideration, rather personal comfort and preference as well as sleeping position and spinal alignment when laying down. Of course trying to work out how comfortable a mattress is from lying on it for a few minutes isn't that successful, but I guess it's better then nothing. (And I don't know if it's the same in the US but here most chains including bed shop chains seem to have exclusive mattresses, the range or at least names of the mattresses are completely different between chains even if the brand is the same. It sounds like there's a lot of dodgy stuff going on with warranties in the US [1].) Nil Einne (talk) 05:11, 31 March 2012 (UTC)

My point was that the bed frame, box spring, and mattress are only needed if you want a very soft bed. If you want a firm bed, much of that is unnecessary. Just a comforter on a shag carpet with padding might even be sufficient. But, if you want to spend extra money to be conventional, you certainly can. StuRat (talk) 05:20, 31 March 2012 (UTC)

I don't think it's just a matter of being conventional, having the bed too low down can make it difficult to get in and out of, particularly if you're old. Being so low down also makes engaging with other people in the room that aren't on the bed odd. Elevating the mattress may also allow stuff to be stored under the bed and makes cleaning easier (putting the mattress directly on the floor isn't going to completely stop dust and dirt going under it). In some countries the 'box spring' you keep speaking of is fairy uncommon, possibly present in fold out beds but little else. If you have flexible supports it's usually in the form of flexible slats, but in other cases, any sort flexible base is rare, when people do have mattress on the floor, it's primarily to save money, not because they think it's better. Nil Einne (talk) 08:33, 31 March 2012 (UTC)

If the box spring has a use I have yet to figure it out; I think it's basically cosmetic, a bustle for a piece of furniture. My gut reaction is that having beds raised off the ground at all is an elaborate contraption designed to keep people free from rats and thus the bubonic plague, but I'm unaware of evidence for this. But checking our article on bed it does mention that in Germany raised beds became popular around the 13th century as "luxury increased" (which indeed was a consequence of the plague, which relieved the earth of some of its burden). I suppose it's even possible that the change was accomplished by natural selection, with no conscious awareness of the reason! Wnt (talk) 14:06, 31 March 2012 (UTC)

To solve the issue of the top of the bed being too low, perhaps placing the mattress above a set of drawers would make most sense. This would dramatically increase storage area in the bedroom and not allow dust to accumulate underneath. (You wouldn't want handles that stick out, but rather indentations in the front of each drawer that could be used as hand-holds.) I've seen this approach done with waterbeds, but not with a regular mattress. I wonder why not. Is there a concern that bedbugs would have more places to hide ? StuRat (talk) 14:16, 31 March 2012 (UTC)

You haven't seen this done with a regular matress, Stu? In my (UK) experience it's very common. The base of the bed comprises a fabric-covered wooden frame (usually on castors) with 4 large recessed-handled drawers, two each side, occupying its full volume, and with a solid, fabric covered top about 15" off the floor on which any design of mattress matching its dimensions (which are standardised to the standard bed sizes) can be placed. (Single-bed versions may have only two drawers.)

The frame usually comprises two 2-drawer halves (head and foot ends) for ease of transport, which are firmly attached together in situ; the drawers are commonly used to store spare bed linen and clothes: bedbugs are not very common in the UK, and in any case I understand that they prefer crevices and cracks in walls and furniture rather than clothes, so this type of bed would not increase their prevalence; a bigger worry would be clothes moths, but one takes the usual elementary precautions against them as in any other clothes drawer or wardrobe.

I've been sleeping on such a bed for nearly 25 years (and for several years one of the family cats liked to sleep on my socks in the drawer immediately under my head end/side, which I therefore left open a few inches for her convenience).

Oddly, our main article Bed doesn't describe or name this exact type, but it's briefly described at the end of Platform bed as a "storage platform bed". Examples can currently be seen in any furniture or specialist bedding shop in the UK. {The poster formerly known as 87.81.230.195} — Preceding unsigned comment added by 90.197.66.209 (talk) 17:53, 31 March 2012 (UTC)

Yes, those beds are quite common. The flaw I've found with them is that you need the bedroom to be about twice as wide as the bed if you're going to be able to make full use of the drawers without needing to move the bed in order to get into them. --Tango (talk) 19:03, 31 March 2012 (UTC)

Well, it's only a flaw if you actually have a very narrow bedroom. Obviously, one should always choose furniture suitable for the room in which it's to be used. {The poster formerly known as 87.81.230.195} 90.197.66.209 (talk) 23:13, 31 March 2012 (UTC)

You can also get a storage bed where the mattress lifts up and the whole of the bottom of the bed becomes accessible. This would solve the problem of narrow rooms. --TammyMoet (talk) 08:25, 1 April 2012 (UTC)

Bed#Types of beds includes:

A captain's bed (also known as a chest bed or cabin bed) is a platform bed with drawers and storage compartments built in underneath.

Captain's bed (currently a redlink) may not be the more common name for this, but it is the one I am familiar with. -- ToE 01:11, 1 April 2012 (UTC)

Yes, I noticed that that was the nearest description in the Bed article to what we're talking about, but to me the term implies one side being flush against the wall (or bulkhead), rather than with drawers etc on both sides. When I went shopping today I meant to ask in a bedding shop what they call it, but it being Sunday that particular shop was closed. {The poster formerly known as 87.81.230.195} 90.197.66.103 (talk) 14:41, 1 April 2012 (UTC)

Silicone rubber lids

I have a nice set of cookware from Anchor Hocking. They are glass bowls suitable for storing, microwaving, and serving food. However, one deficiency is that they have plastic lids which warp if subjected to microwaving. This makes it necessary to remove the lids and place paper towels over the top to catch any splashes, and the paper towels sometimes fall into the food. So, I'm wondering why they didn't make the lids out of silicone rubber.

1) Is it prohibitively expensive ?

2) Does silicone rubber have a coefficient of thermal expansion that doesn't work with glass ?

3) I read that fillers used for silicone rubber can emit annoying fumes, would that be the reason ? Are there no fillers which don't do this ?

4) Also, could the lids be made of clear silicone rubber, or would they need to be colored ?

StuRat (talk) 14:28, 31 March 2012 (UTC)

I don't see why it couldn't be done. In fact, if I'm not mistaken, we (meaning my wife and I) have a lid made of silicone for a glass bowl. Dismas|^(talk) 14:41, 31 March 2012 (UTC)

Clear or colored ? Have you microwaved it with the lid on ? If so, were there any fumes ? StuRat (talk) 15:13, 31 March 2012 (UTC)

I looked in our cabinets but can't find the lid right now. But I do remember it being less rigid than plastic. It's blue in color and there were no fumes. When I microwaved with it, I popped the top to keep it from building pressure. But yes, I microwaved with it. Dismas|^(talk) 15:23, 31 March 2012 (UTC)

I have this silicone lid product [2], which has several uses. I use it on the stove top, in the microwave, and as a jar opener. I've never noticed any fumes, and it comes into contact with hot food all the time, yet does not stain or discolor. SemanticMantis (talk) 15:48, 31 March 2012 (UTC)

Interesting, it doesn't fit on a pot, but is placed directly on the food. This makes it seem more likely that there is some problem with getting it to fit, such as a different coefficient of thermal expansion than the pots. StuRat (talk) 06:34, 2 April 2012 (UTC)

Dow Corning claim you can have transparent silicone rubber[3] but it seems to be more commonly colored. --Colapeninsula (talk) 13:41, 2 April 2012 (UTC)