Wikipedia:Reference desk/Archives/Miscellaneous/2017 October 5

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October 5

Best GU10 bulb

"GU10" is the mechanical definition of a lamp having a 2-pin twist-lock mount, also referred to as IEC 60061-1 (7004-121). The OP's task lamp may be a balanced arm type. Here are reviews of some bulb types. Be sure to heed this warning: a man working at a desk in a confined space with only the light from a low-wattage lamp will nurture furtive ideas and produce degenerate programme material.- BBC guideline in 1949. Blooteuth (talk) 22:51, 5 October 2017 (UTC)

The environment is a room with little natural light and one 15 W LED bulb as a main light. I would like a GU10 bulb for a task lamp that is suited to reading small black-and-white text---colour rendition is not terribly important in itself. Whilst, as aforementioned, there is little natural light anyway, sometimes there is almost none as I work late at night. Given what I have said, what would be most suitable? If the question is presently unanswerable, what additional information is relevant? I am not terribly fussed about efficiency as ergonomic considerations when working take precedence over energy saving (for me, anyway, I do get eyestrain from using poor-quality lighting).--Leon (talk) 19:42, 5 October 2017 (UTC)

Although "colour rendition is not terribly important", for reading, CCT (correlated color temperature) towards the warm end of the spectrum (around 2500K~3500K) is less stressful on the eyes (e.g.: 7000K CCT can lead to eye fatigue). (More info here) — 2606:A000:4C0C:E200:65A7:28DA:7F79:4E50 (talk) 22:12, 5 October 2017 (UTC)

Is that physiological or psychological? Sagittarian Milky Way (talk) 00:17, 6 October 2017 (UTC)

Blue light gives you higher resolution, due to the shorter wavelength (think precision instrument) but it also impedes sleeping. Windows 10 actually has a display setting that lets you tint the screen blue during the day, and red at night, or during which hours you choose. I dim the house lights and tint the screen red about an hour before bedtime. At that point I either magnify the text or use reading glasses for printed material. Scientific American.μηδείς (talk) 00:28, 6 October 2017 (UTC)

The reference Medeis/μηδείς just gave does not support her claim that "Blue light gives you higher resolution", and in fact there are almost no blue cones at the center of the fovea. The maximum density of blue cones occurs in a ring about the fovea. Consequently, the maximum acuity for blue light is lower than that of other colors and occurs approximately 1° off center from the high-visual-acuity fovea. Also see Filling-in of the foveal blue scotoma (Vision Research journal 2001 Oct; 41(23): 2961–2967. ). --Guy Macon (talk) 01:28, 6 October 2017 (UTC)

Interesting, thanks. Unfortunately I took neurology in the late 80's, then said eff it, and finished my biology major with a specialization in botany. Never studied the eye as a whole after Bio 102. In any case, the remainder is recently well-documented. μηδείς (talk) 01:58, 6 October 2017 (UTC)

References

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If I get a round tuit I'll try to find sources; for now, see (maybe): Scotopic vision & Purkinje effect & Kruithof curve ...at any rate, further discussion not related to the OP's query is better done over at the science desk -- That being said, "warmer" colors (lower levels of green/blue light) have less stimulation of photoreceptors (specifically, rods). 2606:A000:4C0C:E200:65A7:28DA:7F79:4E50 (talk) 02:14, 6 October 2017 (UTC)

@μηδείς: do you use, or have you tried f.lux? 2606:A000:4C0C:E200:65A7:28DA:7F79:4E50 (talk) 06:16, 6 October 2017 (UTC)

The functionality built into Windows 10 has the same effect you see at the f.lux article. What the actual app is called, I know not. But in effect, yes, I use at least an analog of f.lux. For table lamps I use incandescent bulbs set on dimmer switches only. (I have looked for grey or brown bulbs, but have had trouble finding any.) For overhead/room lamps I always use non-dimmable bulbs, since the whole purpose of those lamps is to illuminate the entire room as well as possible.

I miss the Giuliani Administration, because at least back then you could call the local precinct and have the sunlight, temperature, or local weather changed to something more reasonable. Bloomberg's "green" reforms were a disaster. μηδείς (talk) 18:45, 6 October 2017 (UTC)

Which reminds me of a joke: I phoned my local precinct; I said, "I want to report a nuisance caller", he said "not you again". —2606:A000:4C0C:E200:65A7:28DA:7F79:4E50 (talk) 21:35, 6 October 2017 (UTC)

Which reminds me of this one: "Is this the complaints department ?" ... "Yes it is, and let me start by saying that you have a horrid toupee, your shirt doesn't match your pants, you have bad breath, and your shoes are cheap. Will you be needing any more today ?" StuRat (talk) 22:44, 6 October 2017 (UTC)

Did you come in here for an argument? --47.138.160.139 (talk) 20:36, 8 October 2017 (UTC)

Okay, what about halogen vs LED? At the moment I have a 35 W halogen bulb there (a) because the lamp came with it, and (b) because they're alleged to give very "white" light. But I'm not sure if it's really ideal?

The remarks about colour temperature suggest that a warm white bulb would be most suitable. Is there any downside to buying cheap LED bulbs vs more expensive, branded ones?--Leon (talk) 07:57, 6 October 2017 (UTC)

The equivalent brightness (lumens) to a 35 W halogen for a LED is about 7 W. Considering how long they last, even a semi-cheap LED costs less in the long run. I personally prefer brand-names (mostly for the reliability the electronic circuits), many are much cheaper than they used to be, . Another thing to consider is dimmable vs non-dimmable; for dimmable, cheap LEDs tend to buzz or hum. 2606:A000:4C0C:E200:65A7:28DA:7F79:4E50 (talk) 08:26, 6 October 2017 (UTC)

Colour temperature preference IMO depends a lot on what you are used to than people give credit for. Most people in European ('Western') countries, including of course North America and NZ+Australia seem to prefer warmer lights often in the 3500K or lowwer for home usage, especially in relaxing settings (e.g. the living room, reading). But there seems to be a preference for higher colour temperatures in parts of East and South East Asia (not sure about South Asia). [1] (not the best ref, but I'm lazy to dig up another one mostly because it's not a particularly strong or important claim). This could be genetic (see e.g. [2] [3], but I strongly suspect cultural issues. Fluorescent lights tended to be associated with offices etc until the widespread availability of CFLs in most European places whereas they seemed more common in homes in parts of East and South East Asia. And early fluorescent lights (and even early CFLs) tended to be cooler.

Note that despite the common descriptions of the colours, there's no strong evidence I'm aware of that having warmer lights actually increases thermal comfort in cooler environments. See e.g. this [4] which found 4000K generally resulted in higher ratings of thermal comfort than 2700K or 6200K. Personally I find even 4000K is a little too yellow in most situations.

In other words, in terms of pure preference terms, I don't think we have enough information and personally I'd go much more by what sort of colour temperature you generally prefer than by what random people tell you you should prefer.

However outside of preference, as indicated above there is increasing evidence that too much blue light at night probably has a negative effect on circadian rhythms and associated negative effects on sleeping, health etc and this is something which most likely be seen in all populations (but maybe within a population there could be fair variation on how strong this effect is). That said, I'm not aware of strong evidence for negative or positive effects of colour temperature on eye strain among worldwide populations, this and the sources above strike me again as the sort of thing based largely on anecdotal claims and personal or group preferences and also situations such as computer displays which may not carry over in to room illumination.

Nil Einne (talk) 13:34, 7 October 2017 (UTC)

I recall from a class called something like 'Engineering Application of Color Theory' that rods are only stimulated by light in the green-blue range (i.e. cool); and reducing stimulation reduces "eye strain" (more accurately, perhaps: "brain strain"). This study seems to suggest that under certain conditions, pupillary response is also affected by color luminance: [5] 2606:A000:4C0C:E200:1DF7:C3BD:258E:E025 (talk) 21:23, 7 October 2017 (UTC)

As for the halogen versus LED debate, I'd recommend LED, unless it's cold in that room and you would actually appreciate the extra heat the halogen lamp will put out. 15W is very little, and I'd want as much light as I could get at that wattage, which would mean an LED. This site claims this LED version uses 86% less energy and lasts 20 times as long as a 50W halogen: [6]. StuRat (talk) 23:49, 7 October 2017 (UTC)

September 11

Are any remains of the planes from September eleventh 2001 still around anywhere — Preceding unsigned comment added by SparkyHelper (talk • contribs) 22:42, 5 October 2017 (UTC)

Yes. μηδείς (talk) 23:49, 5 October 2017 (UTC)

Engines and landing gears were found several blocks away. I don't see why they'd destroy them. Sagittarian Milky Way (talk) 00:15, 6 October 2017 (UTC)

"Gear" in that sense is not a count noun (like cogs) but singular in form, like machinery. μηδείς (talk) 00:30, 6 October 2017 (UTC)

You know what grinds my gears? How mechanics study mechanics to work on mechanics. We need to take back "grease monkey", for clarity's sake. InedibleHulk (talk) 01:27, 6 October 2017 (UTC)

Did computers study computers to work on computers? Sagittarian Milky Way (talk) 01:40, 6 October 2017 (UTC)

The aircraft parts were sorted into shipping containers - New York had containers at Freshkills landfill to store plane parts. Parts of the PA plane were acquired by the National Museum of American History [7]. Rmhermen (talk) 01:00, 6 October 2017 (UTC)

No. The planes were holograms; the "parts" were planted by invisible stealth helicopters. The "real" planes are ... uhm, ... (I forget) 2606:A000:4C0C:E200:65A7:28DA:7F79:4E50 (talk) 01:08, 6 October 2017 (UTC)

Bullshit. Everyone knows holographic jet fuel can't melt steel beams. (((The Quixotic Potato))) (talk) 08:31, 6 October 2017 (UTC)

Some of them (including the landing gear mentioned above, as well as a fuselage panel from the Pentagon plane) are on exhibit at the 9/11 Museum in New York (been there, saw it myself). 2601:646:8E01:7E0B:D403:68F1:A297:C74A (talk) 01:27, 6 October 2017 (UTC)

Fuselage panel can be seen here: [8] but the landing gear are not among the "on display" images. Rmhermen (talk) 01:48, 6 October 2017 (UTC)