Wikipedia:Reference desk/Archives/Science/2014 April 19

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

April 19

What flowers are these?

the pink and white ones --78.148.106.196 (talk) 09:23, 19 April 2014 (UTC)

Could they be all white flowers which have been given red dye, at the stem ? StuRat (talk) 10:12, 19 April 2014 (UTC)

They are carnations, or Dianthus caryophyllus to give them their full name, and some of them look like that naturally. --TammyMoet (talk) 12:47, 19 April 2014 (UTC)

Yes, no dye used. They have been bred to look like this. (Red and white are natural colours for Dianthus, but this combination does not occur in the wild.) Dbfirs 06:40, 20 April 2014 (UTC)

Theme park rides

Are theme park rides designed by civil or mechanical engineers or both? Clover345 (talk) 09:50, 19 April 2014 (UTC)

That would be mostly mechanical engineering, but often some civil engineering (and several other disciplines) would be involved. If you read those articles they are fairly clear (though I was surprised to see a picture of the International Space Station in the lead of the civil engineering article).--Shantavira|^{feed me} 10:47, 19 April 2014 (UTC)

Really? I thought most of it would be structural and geotechnical engineering. I can understand the mechanical elements if it being mechanical engineering but what about the track structure, support structure, foundation, ride station etc. Clover345 (talk) 13:24, 19 April 2014 (UTC)

Why not perform a case-study? Let's take a look at a project orchestrated by Walt Disney Imagineering from two aspects: the portions of the project under the creative direction of the Disney group; and the portions of the project that are inevitably contracted to other companies.

Wikipedia has thorough articles on about every major theme park attraction: for example, the latest mouse ride.

You can also see what type of people Disney hires: the Disney Imagineering Professional Internships careers page has a lot of openings for (...you guessed it...) software, graphics design, business and marketing. There are some openings for the more hard-core engineering disciplines, but those are pretty rare. A recent humor-article on Cracked, 6 Things Nobody Tells You About Working at Disney World, focused on the in-park internships, and provides an interesting insight into the types of work a Disney corporate intern or employee can expect. Once in a while, you might even find something as technical as Animatronics Intern.

So, if Disney has decided to focus on the creative side, somebody else must be engineering and constructing the projects. Possibly the most famous cases are the Monorails at the Disney resorts. Famously, ALWEG engineered and built the first monorail in 1959; and in the 1960s they were replaced by MBB. Disney also operates a cruise line; but as the animation and film industry has little overlap with the operation of a large marine vessel, they subcontract the operation to BAE Systems. I specifically recall the Disney World Skyway at the Florida park; that item was built by Von Roll Holding, an industrial conglomerate that's mostly owned by Bombardier Inc.. Its construction and operational history is plagued by drama, and it has always inspired me to research the conglomerates who build my ski-lifts. (My favorite resort has a huge poster of the commando-looking engineers from Doppelmayr construction firm moving massive construction equipment over cliffs in the Sierra Nevada mountains - you can see some historic photos in their brochure series, Die Welt der Seilbahnen). The recurring theme you might see is that Disney subcontracts the heavy-lifting to major engineering and aerospace conglomerates - groups like BAE and Bechtel and Lockheed. In return, Disney Corporation helps out the defense industry reciprocally by camouflaging aerospace and defense factories so they look like theme parks from the air. But in all seriousness, if you're the sort of person who is attentive to detail, the next time you walk around a Disney-branded theme-park, you might start spotting the not-so-subtle corporate logos of a lot of other companies - particularly, the aerospace and defense supergiants - plastered on the sides of all the mechanical parts of the ride. Most kids are too busy paying attention to the cartoon characters to spot that stuff.

But the reality is, very few corporations have the expertise in the sorts of specialized engineering that a theme-park ride actually requires. Structurally, it requires moving around massive quantities of heavy material and equipment and setting up construction-facilities in remote swampland. This is the sort of thing that military logistics contractors and oil companies excel at: mobilizing the manpower and engineering to construct massive single-purpose projects; over-engineering complex-systems to provide simplicity, safety, and (best-effort)-idiot-proofing.

These corporations hire civil engineers, mechanical engineers, aerospace engineers, a wide variety of technicians and experts, and they directly hire (and subcontract) for a large volume of unskilled labor. If you want to work on such a project, you have a better chance applying to, say, Boeing or Schlumberger, than Disney; but you still have to be really talented and lucky and competitive to get assigned to a really cool theme-park project.

Meanwhile, Disney Corporation handles the branding and the marketing, and the "theming" of the park.

If you study major theme parks operated on behalf of other conglomerates, you will probably find the same trends.

Nimur (talk) 17:07, 19 April 2014 (UTC)

thanks for the detailed answer. Wouldn't most parks employ a small engineering team though, maybe within their project management group? Clover345 (talk) 17:41, 19 April 2014 (UTC)

I think most theme parks, even the ones owned by companies that do nothing but operate theme parks like Cedar Fair, don't design and build their own rides. Individual parks probably don't have enough new construction on a regular basis to justify a full-time engineering department to design them. But there are several companies that do specialize in theme park rides like Mondial, Bolliger & Mabillard, and Intamin.

As for the original question, I imagine it would depend on the type of ride. For something relatively simple like a conventional roller coaster or river rafting ride, I imagine it would probably be about equal between the mechanical and structural designs. But for more exotic rides like roller coasters launched with linear induction motors and things like this, the mechanical design is probably a little more involved. Mr.Z-man 17:42, 19 April 2014 (UTC)

I imagine that most modern theme park rides also involve a fair bit of electrical engineering and computer engineering for the power, automation, and safety features. shoy (reactions) 13:45, 21 April 2014 (UTC)

Innovationin engineering and design

Do you think all engineering disciplines have just as much scope for innovation as each other? Clover345 (talk) 16:35, 19 April 2014 (UTC)

I think it's reasonable to accept that as a starting position and instead put the onus on arguing that they don't. — Lomn 16:50, 19 April 2014 (UTC)

I don't think "innovation" is well-defined or easily-compared, either. It is nearly impossible to provide a total ordering amongst various innovations, so we can't say whether one accomplishment was more innovative than another.

In my experience, "innovative" people need to be generalists who have the ability to quickly become the best specialist on the team. That means you have to be able to become the best at every branch of engineering. Today's problem might be software; tomorrow, it might be glue that isn't sticky enough; and in two weeks, it might be a budget shortfall. Innovation is being able to come up with a new solution that is better than the existing solution, no matter what today's problem is. As my co-worker jokes - "we're software engineers, which is why we have so many oscilloscopes." Nimur (talk) 17:18, 19 April 2014 (UTC)

I would think that in some engineering fields, it's innovate or fail, like consumer electronics, while other engineering fields are far more conservative, like civil engineering, since a new bridge design which collapses because it wasn't completely understood will cause massive lawsuits. See Tacoma Narrows Bridge (1940).

Airplane design is a field where you might think innovation would be needed, but innovations in that field often cause crashes, due to unknown forces and processes, like supersonic flight (turbulence and sonic booms), rectangular windows (force concentration and metal fatigue), composite materials (delamination), and lithium batteries (flammability). Of course, some innovation is needed, but everything needs to be thoroughly tested before it goes into production there, so being conservative makes sense in aeronautics. An exception might be for unmanned vehicles, where accidents are less likely to cause deaths. StuRat (talk) 19:57, 19 April 2014 (UTC)

So would you say there's more innovation in engineering research than in engineering practice? And what about computer science? Is there innovation in that? Clover345 (talk) 16:26, 20 April 2014 (UTC)

Yes to both, although some areas, like consumer electronics, have a lot of innovation in practice, as well. Some areas of computer science are pretty well set, like database design, while others, like microchip design, are very innovative fields. StuRat (talk) 16:38, 20 April 2014 (UTC)

LED bulbs and inteference

Do LED lamps produce interference they way CFCs do? The article doesn't say anything about it, so I assume that they don't. Bubba73 ^{You talkin' to me?} 18:49, 19 April 2014 (UTC)

CFCs usually refer to an unrelated chemical. Are you sure you don't mean CFL, as in compact fluorescent lamp ? Nimur (talk) 19:20, 19 April 2014 (UTC)

Yes, I meant CFL. Bubba73 ^{You talkin' to me?} 20:02, 19 April 2014 (UTC)

So, who you got winning the Grey Cup this year? --Jayron32 22:28, 19 April 2014 (UTC)

Yes, LED bulbs can produce electromagnetic interference. The references I have found (here, here, and here, to start) suggest that this comes from the power circuits driving the LEDs, rather than from the LEDs themselves. There seems to be some wide variance in EMI produced by LED bulbs depending on the type and the manufacturer. - Eron^Talk 19:06, 19 April 2014 (UTC)

I'm getting terrible interference on my electric guitar. Most of the bulbs in our house are CFLs. Some are incandescent and some are LEDs. I'm replacing CFLs by LEDs as they go bad. Bubba73 ^{You talkin' to me?} 20:17, 19 April 2014 (UTC)

You may be getting that interference over the power line, not RF through the air. I experimented with a strat with single-coil pickups, walking around with it hooked up to an iPod via iRig (so there's no ground loop or other mains connection at all) and I can only get an audible buzz when the pickup is < 10cm from the CF bulb's base. With most light fittings, I can't get the pickups close enough to the source of noise for any buzz to be evident. Instead of the expensive business of changing out the bulbs, you might like to first look at eliminating ground loops and, if that's not enough, install a power conditioner in front of the amp. -- Finlay McWalterᚠTalk 10:41, 20 April 2014 (UTC)

I'd go with Finlay McWalte to look at ground loops first. But a word of warning. Some guitarists, having got rid of interference, have then dropped dead the moment they grab hold of the mic (which in my day had chromium plated metal grip and driven by a separate amplifier). Run your problem by a qualified electrician who will know about Z's (simplest way I can put it). If he likes your genre, it won't cost you nothing and may save your life. Also, some stages have power sockets from three different phases. An electrical fault in your equipment can result in lethal voltages between equipment which may be plunged in to different sockets. Modern regulations endeavour to prevent this, but for example: Australians can still plug a hair drier into a socket in their bathroom because the regulators don't believe that their citizens would be so daft as to dry their hair whilst sitting in the bath. Hum. Most Australians I've met are far from daft – but I did say 'most'. So, I think you would be better off genned up on ground loop so that you know how to inform and describe to an electrician your issue.--Aspro (talk) 20:43, 20 April 2014 (UTC)

But isn't Australia better off without those people who see no problem in bathing with their hair dryers ? :-) StuRat (talk) 04:36, 21 April 2014 (UTC)

Eliminating ground loops in house circuits is not a good idea. Most electricians won't know what it is and most residential codes do not allow isolated grounds. Hospital grade outlets and dedicated circuits are really the only foolproof way to eliminate ground loops in power lines. If you still have noise with an isolated circuit, the next step would be to see if the chassis ground can be isolated from circuitry ground. That prevents the neutral/earth ground loop. Do not ever float the chassis to eliminate the noise as it must be tied to earth ground. Noise from CFL's can be propagated on the power line and across transformers so air distance is not very important (X10 and other high freq data is propagated on power lines as well). --DHeyward (talk) 03:37, 22 April 2014 (UTC)

Power factor ?

CFL's seem to create some type of weird problem with the power factor or some such thing, which I've observed when I put them on the same circuit with a regular fluorescent light, all triggered by a motion detector. The lights wouldn't start until I added an incandescent bulb to the circuit, too. I wonder if LED lights also have this problem, or if they would work like an incandescent and smooth everything out ? StuRat (talk) 19:51, 19 April 2014 (UTC)

The motion detector is probably trying to bleed through a small current through the CFL to operate itself, so it may need a lower resistance item in the circuit to work. Graeme Bartlett (talk) 20:40, 19 April 2014 (UTC)

So do CFLs have high resistance, until they turn on, then drop to low resistance ? And would LEDs exhibit this behavior, too, or behave like incandescents ? StuRat (talk) 21:18, 19 April 2014 (UTC)

If I'm not mistaken, CFLs do have a high resistance at first because enough power has to be put into them to get the gas inside to fluoresce. Once the gas is fluorescing, then the resistance goes down. That is one of the problems (only one?) in getting CFLs to dim. LEDs can and do dim depending on the power that they are supplied, so I would expect them to allow a certain amount of power through without any observable light. Dismas|^(talk) 03:01, 20 April 2014 (UTC)

Interesting. So dimmable CFLs should work then, too ? StuRat (talk) 03:05, 20 April 2014 (UTC)

Good luck. Dimmable CFLs don't even work with all dimmers (I know, because I have one). As for LED's, It would seem to depend on the circuitry used for lighting but they can have ballasts, too, and that circuit combined with the motion sensor circuit would determine how "on" is achieved. --DHeyward (talk) 03:37, 22 April 2014 (UTC)

Yottabytes stored in all servers worldwide?

Does of you have any reliable information on how many bytes of data (ranging from text to movies) are stored in all the servers worldwide? One server alone in Utah is said to be able to store 1 yottabyte of data. 112.198.90.173 (talk) 21:20, 19 April 2014 (UTC)

Wired handwavily estimated that NSA's Utah Data Center could "handle yottabytes" (where "handle" does mean "store"), but Forbes estimated (with slightly less guessing, but still lots and lots) that it could store "3 and 12 exabytes", much less than a yottabyte. -- Finlay McWalterᚠTalk 21:44, 19 April 2014 (UTC)

"Handle" might mean "process". So, they might well process 1 yottabyte of data in a year, but only decide 3 and 12 exabytes of it is worth storing. StuRat (talk) 00:51, 20 April 2014 (UTC)

Grr, I meant to write "Handle" does not mean "store". -- Finlay McWalterᚠTalk 08:36, 20 April 2014 (UTC)

But are there any data how many bytes of data of humankind ranging from private data to govern databases are currently stored in the servers of the world, meaning the sum of all data produced by humankind since inception of data gathering? 112.198.90.161 (talk) 07:05, 20 April 2014 (UTC)

Our articles on Exabyte and Zettabyte have better information than Yottabyte. Dbfirs 07:17, 20 April 2014 (UTC)

No. Companies tend to keep that kind of thing secret. We can place some limits based on the number of hard drives sold. That suggests a few tens of Exabytes at most.©Geni (talk) 10:13, 20 April 2014 (UTC)

That's only data stored online, though (meaning "quickly retrievable", not "Internet accessible"). The amount of data archived on tape may be orders of magnitude higher. "The sum of all data produced by humankind" would be still larger, since a lot of it has been lost. For example, the Large Hadron Collider's detectors produce about one petabyte per second of raw data, which would fill the entire world's supply of online storage in a matter of hours. The vast majority of it is discarded without ever being written to disk (they try to keep the most interesting events). -- BenRG (talk) 00:46, 21 April 2014 (UTC)

Replacing harmful flora with innocuous flora as a cure

You have probably already heard of people with colitis being treated by cleansing their intestinal tract and then deliberately repopulating it with a collection of different organisms, usually obtained from a healthy individual. It made me wonder about other ailments that arise from a disturbance in flora. For instance there's a suggested relationship between certain species of Malassezia (a yeast) and dandruff and seborrhoeic dermatitis and related skin disorders. Would it not be a good idea to try to cleanse the skin and then supplant those yeasts with less problematic ones? The same with acne, too. When I was a spotty kid, I got some sort of infection in the corner of my mouth which was easily treated with an antibiotic cream and didn't come back. The cream also reduced my spots but they came back after discontinuation of that cream. Maybe if I'd replaced the bacteria with a type that didn't have any involvement in acne, I'd have been "cured". I'm reckoning there are other afflictions that could be handled similarly but can't think of any at the moment. Do my suggestions make sense or is there a flaw I'm not seeing? I guess obtaining the alternative flora in appropriate ratios might be difficult. I know those "good bacteria" yoghurts are a crock because they don't represent the variety of bacteria in a healthy intestinal tract. --129.215.47.59 (talk) 22:52, 19 April 2014 (UTC)

The difference is that you can control which organism enter your intestines more easily than the bacteria which contact your skin. But, in areas where the person can control what goes in and out, your suggestion does make sense. For example, vaginal yeast infections could be controlled by introducing "good" organisms. (Douching seems to be the cause of many yeast infections, because it removes those good organisms.) StuRat (talk) 23:18, 19 April 2014 (UTC)

• For reference, the OP seems to be hinting at gut flora and perhaps fecal transplants. Also probably the human microbiome. Last sentence seems a bit WP:SOAP, but we do have articles on yogurt and Fermentation_(food). That will be a good start with references, I'll think more and come back later :) SemanticMantis (talk) 23:28, 19 April 2014 (UTC)

The last sentence might be incorrect but was based in the fact that there are hundreds of species of bacteria in the healthy gut and there are less than 20 in probiotic yoghurt. Finding sources for how many different yoghurts contain is proving difficult. I've only found two sources so far. "It has three times the amount of probiotics that are in yogurt. This is because of the fact that in order to ferment a milk with kefir, 10 to 20 different types of probiotic bacteria and yeasts should be mixed" "A popular brand called Lifeway has 12 species or cultures." 129.215.47.59 (talk) 01:18, 20 April 2014 (UTC)

It's possible that only a few are often lost from the intestines, and in need or replenishment. StuRat (talk) 03:03, 20 April 2014 (UTC)

The reason your acne came back was because it's etiology is more complex than a simple bacterial infection (it is caused initially by hormonal changes) and the treatment didn't last long enough. It usually takes a number of months to clear it up. see [1]. Richerman (talk) 09:55, 20 April 2014 (UTC)