Wikipedia:Reference desk/Archives/Miscellaneous/2013 January 23

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January 23

Eye exams (not a request for medical advice)

Is it true that when you go to an eye doctor and they do a checkup for any potential problems, they put in special eye drops that render your vision temporarily blurry? If so how long does it last? And what is the solution made out of? 70.55.108.19 (talk) 02:52, 23 January 2013 (UTC)

It is true. there are all sorts of drops. This site says dilation can last 4-24 hours. I have driven home after eye exams without a problem, so a basic exam may not be hugely disturbing. Ask your doctor what to expect and how to behave. μηδείς (talk) 02:59, 23 January 2013 (UTC)

It is true. It usually lasts a few hours. I'm not sure what the fluid is. The site describes the exam but just says "drops" are placed in the eye: http://www.nei.nih.gov/healthyeyes/eyeexam.asp RudolfRed (talk) 03:02, 23 January 2013 (UTC)

If it may cause stinging, is it necessary to warn your doctor that your eyes may be sensitive? My eyes burn every time I cut onions or cry. 70.55.108.19 (talk) 03:26, 23 January 2013 (UTC)

You should it discuss it with your doctor. I'd say that's true of any procedure. RudolfRed (talk) 03:30, 23 January 2013 (UTC)

There is nothing by itself irritating with such drops as there is with onions which contain irritating sulphur compounds. You can and should insist on discussing any expected discomfort ahead of time with the doctor, who can and should address your concerns by his actions. μηδείς (talk) 03:42, 23 January 2013 (UTC)

OP, it isn't always true, but it may be true. When I have my eyes checked, there's a fairly thorough check done of various things, without drops. Then, if and only if I can assure them that I've made transport arrangements and will not be driving home, they do some more tests involving drops and blurry vision. The blurriness lasts anywhere from 4-8 hours in my case. -- Jack of Oz ^[Talk] 03:48, 23 January 2013 (UTC)

I won't be going alone, and it'll be my first eye exam and I'm near-sighted without knowing why, so it's very likely they'll end up using those eye drops. I'm just very anxious of what's to come. 70.55.108.19 (talk) 03:53, 23 January 2013 (UTC)

request a sedative if you think it is necessary. I never allow myself to be intubated or drilled upon without a sedative. μηδείς (talk) 04:19, 23 January 2013 (UTC)

It's an eye examination, not a heart transplant or admission to ICU. -- Jack of Oz ^[Talk] 04:51, 23 January 2013 (UTC)

There are two kinds of common drops used to examine eyes. One that dilates the pupil, more of which you can read here and here and fluorescein which is used more often in the emergency department and highlights any scratches or damage on the cornea. The mydriatic drug that opens your pupil causes the blurred vision and the fluorescein is yellow and will make your eye look a little yellow for a short while. Both may be slightly but briefly uncomfortable and you will certainly not need any sort of sedation. Jack has it right - as usual! Richard Avery (talk) 08:20, 23 January 2013 (UTC)

I take that as my first compliment of 2013, thanks Richard. At this rate, I'll have 15 by Christmas.  :) -- Jack of Oz ^[Talk] 10:42, 23 January 2013 (UTC)

Absolutely no need to be anxious. If the examination involves eye drops which temporarily affect your vision, you should be told beforehand so as to ensure you are aware of resrictions on driving etc. But even in this case the effect on vision is, in my experience, minor and the drops are not at all irritating. If you have any concerns, ask your doctor to explain what the examination involves. They will be used to this, it is a common request, and it is in their interests to make you as comfortable and relaxed as possible during the examination. Gandalf61 (talk) 10:40, 23 January 2013 (UTC)

I didn't say there was a need for all people undergoing examinations to be sedated. But having any liquid squirted in your eyes is a highly unnatural and potentially disturbing matter. One of my nephews was fitted for glasses at age four, and I do not blame him for having bitten the bastard who forcibly held him down, separated his eyelids, and dosed him with drops as he lay crying. That being said, 5-10 mg of Valium at a doctor's discretion is hardly asking for a presidential pardon for eating undercooked school children. The OP should be confident to man up if he can do so but also to insist on reasonable doctor-sanctioned palliative care if he needs it. μηδείς (talk) 13:50, 23 January 2013 (UTC)

Yeah... so anyway... as Richard says, the common "drops" are either to 1) dilate your eyes (which will make your vision blurry for a while; about an hour or two), 2) numb your eye so they can test the pressure in your eye to make sure you don't have glaucoma, or 3) to dye the eye so they can see abnormalities. None of them are painful, they all go away quickly, and there's nothing to be concerned about. Shadowjams (talk) 15:02, 23 January 2013 (UTC)

My experience over the years is that eye-numbing has become less common as the glaucoma test has gotten more high-tech. When I was young they had to numb the eye to apply a metal device (a ghastly procedure), but recently I've either had them used a plastic device (still not great but much more straightforward) or an air-puff device (much preferable to anything that touches the eye though still a game you have to play with your blink reflex), neither of which have ever been presented with drops to me. This is anecdotal, of course, and refers to practice in the United States. --Mr.98 (talk) 16:26, 23 January 2013 (UTC)

• The metal device, hopefully not used these days, was called a Tschiotz tonometer. Richard Avery (talk) 19:12, 23 January 2013 (UTC)

My experiences have been similar (also in the United States), although lately it is more and more unlikely that they will test for glaucoma at all if you aren't in the demographic of 'People Who Seem Likely to Get Glaucoma'. I have terrible eyesight and a family history of eye problems but I have to specially request the glaucoma tests since the doctors will not usually give me one. For the last several years, the air puff test has been the way things are done, at least in the offices I have visited. The drops that cause dilation as used to enable the doctor to look at the lens inside of your eye, through the opened iris. Helene O'Troy - Et In Arcadia Ego Sum (talk) 17:22, 23 January 2013 (UTC)

When I see my ophthalmologist every year or two, they do use those dilation drops. The main side effect is that it makes my eyes more sensitive to light for two or three hours. For the trip home, you may want to wear a darkening filter they will give you, that you wear inside your glasses. If you do not wear glasses, use a pair of sunglasses, you should have one anyway. They use a puff test for glaucoma.--Wehwalt (talk) 19:22, 23 January 2013 (UTC)

OK, thanks for the info guys, it actually helps me feel less nervous about the exam itself now. 70.55.108.19 (talk) 22:30, 23 January 2013 (UTC)

• Here's what to expect. μηδείς (talk) 23:10, 23 January 2013 (UTC)

I have the idea already — Preceding unsigned comment added by 201.166.108.122 (talk) 05:08, 24 January 2013 (UTC)

Special education statistics

Where can you find information on the number of special education students in US schools by year (for example, seeing how many there are now compared with, say the 1980s?) — Preceding unsigned comment added by 169.244.148.235 (talk) 14:57, 23 January 2013 (UTC)

Possibly in one of these reports? [1] Rmhermen (talk) 02:56, 24 January 2013 (UTC)

JSDF

Do the Japan self defence forces now consider themselves military? Clover345 (talk) 17:58, 23 January 2013 (UTC)

Japan Self-Defense Forces calls them military. I've not asked every single member thereof what their personal opinion on the matter is, however. --Jayron32 18:12, 23 January 2013 (UTC)

Besides allexperts, Yahoo answers is there another good question free online site that people answer right away?

Besides allexperts, Wikipedia reference desk, Yahoo answers is there another good question free online site that people answer right away? Venustar84 (talk) 19:57, 23 January 2013 (UTC)

There are many many many subject specific forums that fulfill those requirements. Dismas|^(talk) 20:13, 23 January 2013 (UTC)

The IRC channels for help, I'd think.--Wehwalt (talk) 20:33, 23 January 2013 (UTC)

Quick answer do not mean good answers. Yahoo! is pretty terrible, and we aren't always the best either (but we're better than them). Mingmingla (talk) 00:12, 24 January 2013 (UTC)

As I recall, there was a study done of this - and we came out clearly on top. I can't find where it was discussed though...maybe on our Talk: page? SteveBaker (talk) 14:32, 24 January 2013 (UTC)

I believe you're thinking of: Shachaf, P. (2009). "The paradox of expertise: Is the Wikipedia reference desk as good as your library?" Journal of Documentation, 65(6), 977-996.[2] --Atethnekos (Discussion, Contributions) 17:56, 24 January 2013 (UTC)

The Straight Dope Message Board is a general interest site that's pretty good at answering questions. John M Baker (talk) 15:29, 24 January 2013 (UTC)

Succession duty and inheritance tax

What's the difference, if any, between a succession duty and an inheritance tax? – Arms & Hearts (talk) 21:06, 23 January 2013 (UTC)

I am not an expert, but we should probably have only one article. It looks like 2 different names for a range of similar taxations. --Lgriot (talk) 08:58, 24 January 2013 (UTC)

Briticism vs. Americanism. Also called Estate Duty or Death Taxes.DOR (HK) (talk) 08:58, 24 January 2013 (UTC)

Succession duty seems to be an old name. It's always called inheritance tax in the UK these days. --Tango (talk) 12:34, 24 January 2013 (UTC)

Steam train fireman

Why did steam trains have a fireman manually shovelling coal rather than some automated hopper that just fed coal?

It does not seem like it would be beyond the wit of Victorian engineering, what stoped clean and shiny steam punk evolving before diesel replaced it in the 40s? 2.98.130.182 (talk) 21:50, 23 January 2013 (UTC)

Probably an unnecessary complication given that labourers were cheap. -- SGBailey (talk) 22:08, 23 January 2013 (UTC)

Fireman (steam engine)#Mechanical stoker -- Finlay McWalterჷTalk 22:15, 23 January 2013 (UTC)

From our article: firemen are responsible for "raising or banking the fire as appropriate for the amount of power needed along particular parts of the route" -- To do the job requires at least some skill and judgment, not just a continuous feed of coal. SemanticMantis (talk) 22:33, 23 January 2013 (UTC)

Towards the end of the steam-locomotive era, they did have automated stoking. The reason why manual labor was used for so long is that it's easier, cheaper, and more reliable -- mechanical stoking only saw mainstream use once the volume of coal needed exceeded what a fireman could handle with a shovel. --Carnildo (talk) 02:39, 24 January 2013 (UTC)

I'm pretty sure that the fireman had other duties besides the physical shovelling - so you'd probably need to have that guy in the cab anyway, and if he has to be there, he might as well do the shovelling too. There is also always merit in simplicity - less to go wrong. SteveBaker (talk) 14:31, 24 January 2013 (UTC)

It seems that "mechanical stokers" never really caught on in the UK, reasons given in RailUK Forums are;

• "that they were far less efficient than a fireman (who knew when and where to put the coal, rather than just shoving it in). Considering the relatively modest (by US standards) size of British locomotives, they were also not seen as necessary."
• "Moving from one side of the cab to another was no longer a simple movement (the conveyor was in the way)"
• "the flow of coals onto the conveyor was inconsistent and unreliable as the consumption progressed; the stuff just got dumped into the end of the firebox (any fireman knew where to aim the shovel to keep a decent fire buring efficiently, the conveyor didn't)"
• "mechanical stokers needed coal of an optimum size to work efficiently otherwise the conveyor (an Archimedian screw arrangement, usually) would jam with obvious problems for the crew. So there was an extra expense of seeing that the coal was broken up into the right-sized lumps"

Apparently only 3 British locomotives of the 1950s BR Standard Class 9F were experimentally fitted with mechanical stokers; "it was hoped that mechanical stoking might enable the burning of low-grade coal. It was relatively inefficient, and the locomotives used in this trial were rebuilt to the normal configuration. Simply supplying more low grade coal than a fireman could do by hand did not provide efficient burning." I'll stop now in case people think I know what I'm talking about. Alansplodge (talk) 17:27, 24 January 2013 (UTC)

Although not widely used in train steam engines, for the reasons Alansplodge describes, clearly mechanical stoking is a necessity with large-scale power generation from coal. This page from E-On says a 800 MW station needs 60 kg every second, obviously beyond the capacity of any practical number of human stokers. It seems powerplant furnaces are either pulverized coal-fired boilers or later fluidized bed combustion systems. This paper from Hitachi has a diagram of the layout of a such a plant. So stoking is more than just dumb shovelling in of coal, and retrofitting such a system to a manually-stoked design looks, as Alan's links show, to be unproductive. Those modern plants are using a controlled, pulverised coal stream delivered into a combustion chamber designed specifically for a steady, high volume coal stream. And, as the Hitachi paper shows, they use a sophisticated control-feedback loop to manage the fuel inflow (something akin to the skill the human stoker clearly needed). -- Finlay McWalterჷTalk 17:46, 24 January 2013 (UTC)

The fireman (on a US locomotive) had duties besides shoveling coal. He made sure the water level in the boiler was correct (too low and the boiler explodes) and could maximize efficiency of operation and was also the only one able to see what was ahead and to the left (the boiler obscured the engineer's (driver's) view except for ahead and to the right). Even with a stoker (located typically below the floor, not up in the way as suggested previously) the fireman could still shovel coal in when he found it advisable). Union workrules (featherbedding) continued to require a "fireman" on diesel locomotives, many years after steam locomotives went away. He was also a backup for the engineer, like a copilot on an airplane, in case the engineer passed out or something, and could avoid crashing into a stopped train. A "deadman switch" could achieve the safe stopping of the train if the engineer stepped off it. 75.34.28.112 (talk) 20:21, 24 January 2013 (UTC)

It's not just engines; it applies in surprisingly modern contexts as well. An analogy to the role of the stoker on a coal-burning locomotive is the loader in a tank; the role of taking a shell and putting it into the breech of the gun is quite similar to loading coal into the furnace, and the turret of a tank is a similar environment (cramped, busy, etc) to the cab of a locomotive. There are also apparent theoretical advantages in both cases to getting rid of an extra person!

However, most modern Western tanks still use manual loaders; autoloaders have turned out to be quite unpopular, and the other advantages of having a fourth person around outweigh the potential efficiency savings of automation. Andrew Gray (talk) 21:29, 24 January 2013 (UTC)