Science desk
< July 23	<< Jun \| July \| Aug >>	July 25 >

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.

July 24

Meteoritic vugs

This image's description refers to the off-color section at far left as a "vug", and our vug article discusses the subject in terrestrial rocks, but not in meteor(ite)s such as the pictured object. How would a vug form in this context? I can find references to the subject ([1] [2], etc.) plus the results of Google thinking that I made a typo for bug, but nothing answering my question. Nyttend (talk) 00:59, 24 July 2017 (UTC)[reply]

The image description says ''Note the "vug" inclusion on the middle left of the slice', not 'far left'. :) --CiaPan (talk) 05:42, 24 July 2017 (UTC)[reply]

Our articles on this are at Iron meteorite and the yellow mineral would be troilite. From http://www.sciencedirect.com/science/article/pii/S0016703767800279 it appears that when molten, the iron sulfide would be all dissolved with the other liquid metal. Then iron/nickel solidified, leaving a concentrated lower melting point liquid that crystallized troilite ( and other minerals) when it cooled more. I wouln't call what's in the pic a vug. Graeme Bartlett (talk) 13:01, 24 July 2017 (UTC)[reply]

Widmanstätten patterns resemble lines in a typical 60 degree pattern. The sample in the picture looks more like a bad forgery then a real meteorite to me. Obviously allot of money can be made with little effort on selfmade samples like that. --Kharon (talk) 05:58, 25 July 2017 (UTC)[reply]

Comet tail fitting in a suitcase

According to this page, among other comet-related articles and sources I've read, the amount of material in a comet's tail would fit into a suitcase. Is this correct, and if so, how does it compare in density to inteplanetary/interstellar space in general? Also, if this thought experiment could be actually carried out, what would the packed comet tail look and feel like-- dust, packed sand, heavy stone, or something else? 2602:306:321B:5970:997C:317E:34C0:891 (talk) 01:04, 24 July 2017 (UTC)[reply]

I suspect that the comet's tail is far more dense than dust in an average nebula, etc., as those are far larger than the comet's tail width, so a much lower density will block or reflect as much light. From our article: "a nebular cloud the size of the Earth would have a total mass of only a few kilograms."StuRat (talk) 03:37, 24 July 2017 (UTC)[reply]

vacuum also has some examples and digits relative to outer space Gem fr (talk) 09:09, 25 July 2017 (UTC)[reply]

This page says a swimming pool (at the density of water) rather than a suitcase, but that's still a pretty small volume. We can make a guesstimate as follows. The JPL text says that the coma can be "tens of thousands of kilometers across" and the tail "can reach 150 million kilometers in length". So let's assume a tail with a length of 10^8 km and a cross section of 10^5 km^2, so a total volume of 10^13 km^3. Outer space says that the average density of matter in interplanetary space is 10^6 particles per m^3 and most of this consists of hydrogen and helium atoms. That gives a density of about 10^15 atoms per km^3, or about 10^-11 kg per km^3. Multiply by a factor of 100 to account for the higher density in the comet's tail, and we get 10^-9 x 10^13 = 10^4 kg of matter in the comet's tail. So that's bigger than a suitcase but smaller than a swimming pool. Gandalf61 (talk) 09:54, 25 July 2017 (UTC)[reply]

Pipe wrench

What kind of pipe wrench can exert the greatest amount of torque on smooth stainless steel pipe -- an ordinary pipe wrench, a strap wrench or a chain wrench? (Note: it doesn't matter whether or not it will leave marks on the pipe -- what matters is maximum torque and nothing else.) 2601:646:8E01:7E0B:A51C:A8E5:DDE4:3E35 (talk) 06:13, 24 July 2017 (UTC)[reply]

The longest one - assuming none of them slip. Torque and grip are different things. 196.213.35.146 (talk) 08:08, 24 July 2017 (UTC)[reply]

It depends on the diameter, the grade of stainless, and the quality of the wrench.

A chain wrench in particular won't work well on a small diameter pipe. The links are individually rigid, so they provide few contact points around the pipe. Achieved torque owing to grip is dependent on contact area, even though friction in most theoretical models isn't (and that whole independent model fails if the friction arises due to an applied clamping force rather than weight). There are some techniques for chain wrenches that allow multiple turn, helical wraps, to get round this problem (a flexible bike roller chain can be used instead of a rigid block chain, but they are easily broken too).

Some stainless pipe has quite a hard surface - a Stillson type pipe wrench with worn jaws may be unable to grip at all, as the pipe surface is too hard to allow the teeth to dig in and engage.

On the whole, you might find (surprisingly) that a strap wrench gives the best grip on the surface of smooth stainless pipe. Although you need a strap wrench designed to withstand such a force, not just a rubber strap to open kitchen jars with. Multiple turns of (natural fibre) rope can be useful too, despite looking archaic.

Also check the assumption that surface damage is acceptable. That pipe is expensively stainless (thus hard to work with for a reason). Damage pits can be a focus for corrosion, for stress risers and for dirt accumulation - all reasons against why stainless might have first been used. Andy Dingley (talk) 08:22, 24 July 2017 (UTC)[reply]

Well, let me rephrase: which type of wrench (out of the 3 types listed above) offers the best grip on smooth stainless pipe of medium diameter (say, 1-1/4 inch)? And yes, surface damage is acceptable within reasonable limits (visible scratches and marring is OK, a mangled pipe obviously isn't). 2601:646:8E01:7E0B:A51C:A8E5:DDE4:3E35 (talk) 09:13, 24 July 2017 (UTC)[reply]

Hard to say without trying the specific tools and pipe concerned. But don't rule out a good strap wrench, with a strong nylon strap and a steel head to fit a ratchet handle. Andy Dingley (talk) 11:02, 24 July 2017 (UTC)[reply]

By design/physics chain wrenches can apply the most torque since they have the most grip but for that they need to fit the pipe well. Pipe wrenches are the next best sollution and they are better suited for different sizes thus they are commonly used by professionals. --Kharon (talk) 05:43, 25 July 2017 (UTC)[reply]

Color of wet rocks

Rocks display characteristic colours. Many types of rock display distinct and attractive colours. When a rock surface is damp or wet the color usually becomes significantly deeper and more intense. What aspect of reflection of light from the surface of rock explains the increasing intensity of color when the surface is damp or wet? Dolphin (t) 12:58, 24 July 2017 (UTC)[reply]

Chatoyance might be a useful term, although from woodworking, not geology. Highly figured wood, such as birdseye maple isn't at its best unless given an oiled finish, or even just wiped with water in the workshop.

The explanation for this is to do with specular vs diffuse reflection, and reflection vs. transmission overall. A raw pebble, even if polished smooth, is still rough at the optical scale. So it acts to give diffuse reflection of any illumination. It looks matt and greyish. Coating it would a smooth-surface (such as a clear liquid under surface tension) is akin to finely polishing it. It now loses the diffuse reflection in favour of a specular reflection. This is also less strong as a surface reflection (its albedo might actually decrease) and the reflection is now from deeper within the rock, influenced by its colours. Andy Dingley (talk) 14:22, 24 July 2017 (UTC)[reply]

I actually asked myself the very same thing, some rainy day.

first, "deeper and more intense" actually means more contrasted. Most solids are, really are, darker when wet. Water absorb light that would had been reflected/scattered.

second, color has examples of how intensity alter color perception

third, most objects are covered by all sort of material of any size, from molecules and microbes to dust and dirt. Water (or oil) will somewhat clean the solid, turning the color disturbance of these thing into just a loss of light.

fourth, same as @Andy Dingley:: a thin liquid pellicle reduce surface color effects (those effects that peak in Structural coloration )

But i am still wondering

Gem fr (talk) 10:12, 25 July 2017 (UTC)[reply]

In order to produce color, light has to enter the rock, be absorbed there at some wavelengths but not others, and be reflected and leave the rock again.

At the interface between air and rock, the difference in refractive index is large, which leads to the reflection of a lot of light (see Fresnel equations for more details) without the chance of wavelength-dependent absorption, and that makes the rock pale.

But water has an intermediate refractive index. Calculate how much is reflected and transmitted in this case at the air-water interface as well as at the water-rock interface, and you'll notice that now more light enters the rock, leading to more saturated colors.

Icek~enwiki (talk) 19:22, 26 July 2017 (UTC)[reply]

I tried in my kitchen, with diffrents things:

a glass tray with colors printed on the bottom and wavelike strips (~1 mm wavelength) on the surface: water just make disappear the effect of the strips, no other color change
a flat but somewhat rough (because of long use) Melamine resin, colored with flower motif. No color change whatsoever, you cannot tell the water/no water boundary unless the angle induce reflection on the water.
a zinc surface. Water make it darker, and when it has completely evaporated, it may continue to show, or not. The darker watermark seems to coincide with former boundary, where surface tension effects where maximum, hinting at some persistent modification of surface (cleaning?).
some colored paper. It got darker
a dusty lacquered thing. Water remove the effect of dust (what a surprise...)
three things made of some sort of engineered wood with veneer. All reflect light in a dull, imprecise fashion, because of a used surface state; this means they scatter light. Water turns two of them darker, and doesn't change the scattering. The third reacted in a somewhat different way: it was slightly darker, but the scattering seems to disappear, the "wood" seems more precise, as if the surface were virgin. This is the only occurrence of an effect of the kind suggested by the question, but even then, the color were not "deeper and more intense", rather sharper, less scattered

In any case, the color never gets deeper or more intense, just darker if any effect occurred

Gem fr (talk) 10:32, 28 July 2017 (UTC)[reply]

Medical printer

While looking for something else, I ran across an eBay listing for a KELLER MEDICAL PRINTER/PULSE OXIMETER/ VITAL SIGNS MONITOR. I understand the idea of something that monitors vital signs, and I've had pulse oximeters applied to me plenty of times, but what's a medical printer? Developing a specific kind of printer just for medical purposes seems a bit of a waste, since computer printers can print stuff of any subject, and printers for lots of different paper sizes and types already exist. Nyttend backup (talk) 13:31, 24 July 2017 (UTC)[reply]

As far I can tell from the pictures, it's either one inter connected device being sold. It's possible the vital signs monitor is seperatable from the pulse oximeter, but I'm not sure how likely this is to be done, especially with a second-hand device. It looks like it's possible the printer component is also separatable, but it's only likely to be used together with the device, unless I guess you have a working device of some sort and just need to replace the printer and it's compatible. The printer component is surely either for real time printing of vital signs as commonly seen on older TV shows and movies or like with this device [3], or for printing stored records e.g. as with this device [4] or both. Even for store records, the reason why you may want the ability to print the records where the machine is and not have to risk relying on a network connection to some other external printer where you'll collect the results seem obvious. By the same token many check out machines either have a built in printer, or are directly connected to one, rather than sending the receipts to be printed in some other location. Nowadays they often are networked so the receipts are generally retrivable and printable in some other location and this may be done for various reasons (and the data will often also be used by the company in various ways too), but it doesn't take away the benefit from having the directly connected printer. Nil Einne (talk) 14:24, 24 July 2017 (UTC)[reply]

The question, though, is "what is a medical printer"? A search for "medical grade printer" gets a lot of hits; they seem mostly but not all to be thermal; many but not all of them still have parallel ports. What makes a printer "medical grade"? --jpgordon^{𝄢𝄆 𝄐𝄇} 14:30, 24 July 2017 (UTC)[reply]

But nothing was said about medical grade printer until now. The OP did ask about a medical printer but, only provided one single example. I did personally think there probably was such a thing as a medical grade printer, since it struck me as the sort of thing that would likely be needed given the requirements (many mentioned here) including supporting whatever required standards and also having appropriate certifications but since the only thing here at the time was am ambigious question, it's not something I bothered to research more than demonstrated above. If anyone the question about a medical grade printer had been asked, I either would have researched it or let someone else answer it but this question only came after I responded. Nil Einne (talk) 16:25, 25 July 2017 (UTC)[reply]

Agreed. Also, a medical printer should be more reliable. Certain printer technologies are too unreliable to be used in a situation where lives could depend on it. For example, the page feed mechanism used in many printers is prone to failure by pulling in more than one sheet at a time, pulling a sheet in off-center, etc., thus causing a jam. The system used on adding machines, where there's one continuous roll of paper fed through a pair of rubber rollers, is much more reliable, and should be used here: [5]. Time is also critical, and the printer shouldn't need to be turned on and given time to warm up, clean the print heads, etc., before it can be used. And finally, it should be possible to sterilize the printer, so all the parts should come apart for cleaning. StuRat (talk) 14:34, 24 July 2017 (UTC)[reply]

Does anyone have any real informed answers, rather than guesses? --jpgordon^{𝄢𝄆 𝄐𝄇} 14:47, 24 July 2017 (UTC)[reply]

The path to truth can be a gradual one, the goal gradually coming clearer in the distance; the odd part is, so long as you are walking it, you have not arrived. In any case, I would guess that if "medical printer" is a phrase with a meaning, the ISO standards would mention it, and searching medical printer ISO I get a variety of promising hints; the top one [6] says that "Our ISO 9001:2008 and ISO 13485:2003 certifications and FDA Registration serve as a testament to our knowledge and understanding of the critical guidelines that are required by the industry." Now, I tend to have more knowledge of relatively inconsequential things like science than the better-paying and more stable field of bureaucratese, so I'll let someone else try to take this from here. Keep walking... Wnt (talk) 15:32, 24 July 2017 (UTC)[reply]

Note that both ISO 9001 and ISO 13485 are Quality management systems standards. The later one specifically for medical devices. The former is general purpose, there was a time when everyone was touting their ISO 9001 compliance. Incidentally, I don't know if this applies to medical devices but there was a time when it came to ISO 9001 as per my earlier comment while you probably wanted a manufacturer/designer who was ISO 9001 compliant/certified, you probably did not want one who made a big deal over their ISO 9001 compliance/certification. They are arguably important, but you should understand what they are and what they actually mean. Nil Einne (talk) 17:09, 25 July 2017 (UTC)[reply]

Keller Crescent Printing made specialized printer equipment and paper, such as label printers for pill bottles and things like that: [7]. I think they no longer exist anymore, it looks like they were bought out in 2007,[8] and many of their plants have since closed down.[9] What this specific device printed labels for, I'm not sure, but it was some specialized printer that output a label. (maybe a readout of the vital signs the machine measures in order to put it on a chart?) --Jayron 32 15:37, 24 July 2017 (UTC)[reply]
I think the item is just being improperly parsed. It's not (medical printer)/(pulse oximeter)/(vital signs monitor), it's a medical item including a printer, a pulse oximeter, and a VS monitor. That is, "medical" really only modifies the latter two portions of the description and a printer is just a printer (which in this case is attached to a medical device). Sort of a purple people eater problem. Matt Deres (talk) 16:10, 24 July 2017 (UTC)[reply]
Right, which explains why there are many many printers on the market sold explicitly as "medical printers". I think Wnt's suggestion is correct; "medical printer" is associated with conformance with particular ISO standards for medical devices and also for medial record keeping. --jpgordon^{𝄢𝄆 𝄐𝄇} 16:30, 24 July 2017 (UTC)[reply]

Well medical grade printers obviously exist, I don't think anyone denies that. But the specific eBay item being sold seems to be as Matt Deres described or I described. The attached printer is most likely designed to only print out information. There's a fair chance it's not designed to print out images, which is what many devices sold specifically as medical printers seem to be for, amongst other things. It would seem likely the attached device is a medical grade printer but a highly specialised one. The standards it may have to meet may be different from a more general medical printer. As I said above, it's possible it's detachable and usable with other devices but this probably isn't that likely to be done in practice and in any case this would only be with similar devices. Nil Einne (talk) 16:31, 25 July 2017 (UTC)[reply]

To give an example of what I mean see this device [10]. Yes it's a medical printer but for a specific purpose. What requirements, standards and certification it has to met, I'm lazy to research but while some of them may be the same, there's a fair chance some of them are different from [11] this device to give another random example. Nil Einne (talk) 16:39, 25 July 2017 (UTC)[reply]

All the flailing around here has to do with philosophy. I mean, is a "medical printer" an intersection of two words, or whatever is called by that phrase. Is it defined as any printer used for medical purposes (like the one on your desk if you use it to print out a report from the hospital)? But most often I think it means a printer that can safely be sold and used for medical work without the local shamans and cartel enforcers turning up to cause accidents for the merchant. People need medicine and therefore there are many, many rackets that must be paid; hence the regulatory definition. But it should be noted that this definition may vary country to country, county to county, howevermuch globalists try to make their "international standards" sound like laws of nature. Perhaps a printer is only "medical" if it cannot print unflattering things about Kim Jong Il (not that I'm a North Korean lawyer). If an armed gang of nihilists broke into your hospital and said you could only print medical records from the printers you'd scribbled red with permanent markers then those would be "medical printers" in your parlance within a day or so. And if violence is truth, then a medical printer is not defined by what it is, but where and when it is also, and even that may only be a best guess with a margin of safety; so long as the Inspector smiles it is a medical printer, and if He frowns, watch out! Wnt (talk) 10:26, 26 July 2017 (UTC)[reply]

Our medical grade printers come from Sony. They are dye-sub, which is more resistant to splashes than ink. They connect directly to most medical equipment. They also produce laminated printouts if necessary. They dye used is also marked medical grade. It is resistant to bacteria and mold. The same with the paper - medical grade. 209.149.113.5 (talk) 16:53, 24 July 2017 (UTC)[reply]

"Keller Medical" is the name of the firm which made the item. So, the item was correctly listed "KELLER MEDICAL PRINTER/PULSE OXIMETER/ VITAL SIGNS MONITOR". As a former medical equipment repair and maintenance technician, I can attest that there's no "waste" involved in making customizing printer gear for medical devices. Either something off-the-shelf is used and re-labelled with the medical device manufacturer's name and model name/number, or (as was when high-resolution ink-jet and laser printers got cheap enough to build into EEG/EKG machines) a combination of a good, small printer head and paper-handling gear are built into, say, a portable electrocardiograph or cardiac defibrillator. The real waste in provision of medical care is how much clinics and hospitals over-bill for medical care (which may actually be cheaper, since they're required or "strongly encouraged" to accept drastic under-billing and even non-payment for services provided under Medicaid and Medicare, than placing ALL medical re-imbursement in the same hands).

Paper printers for medical devices are getting to be obsolete, anyway. Entire medical charts, including EEG and ECG traces and vital signs listings are stored electronically and when such information must go between medical offices, sent either over the Internet, fax machines, dedicated modems, or written to various optical disc formats. loupgarous (talk) 06:38, 28 July 2017 (UTC)[reply]

Strength of non-drug related addictions

How strong are non-drug related addictions? Which on is the stronger? Porn, sex, gambling, adrenaline thrill seeking, sport, internet? How do they compare to drug addictions?--Clipname (talk) 23:39, 24 July 2017 (UTC)[reply]

You may find Addiction interesting. I don't know how you would define "stronger". The impact could vary by individual. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:58, 24 July 2017 (UTC)[reply]

Behavioral addiction could be characterized as less severe than chemical addictions, in that stopping isn't as likely to cause severe physical symptoms, like delirium tremens. Also, many chemical addictions, like alcoholism or smoking, are also behavioral addictions. StuRat (talk) 00:26, 25 July 2017 (UTC)[reply]

Revealingly addiction is often connected to behavíor or consumption, just because someone regards it unhealthy, often with rather far-fetched arguments. So obviously it is disputed when and even if at all behavior and/or use of "soft drugs" can be regarded an addiction. Only on hard drugs everyone agrees that these are addictive, because hard drug withdrawal is well known to make most addicted do anything aka go crazy for a new dose. Since that is clearly only true for the real "hard drugs" it seems wrong to categorize anything else addictive. Else where to draw the line? Are all women "addicted" to chocolate? Are all children addicted to sweets? --Kharon (talk) 05:26, 25 July 2017 (UTC)[reply]

Demonstrably all addiction strengths vary by the person. For instance I had (or perhaps have) a nice little medically induced Endone habit, which I could kick after a week (several times). Cheese, on the other hand... Greglocock (talk) 05:04, 25 July 2017 (UTC)[reply]

@Kharon:I personally define me as addicted to (among other), water, food, and air (oxygen); to my kids, too (and their mother, even more so) ; and pretty much so to chocolate, cheese, and video games (which i can stop wherever i want, as any addicted person will tell you of its addictive habbit). I definitely get crazy when i am hungry (the very same stimulus what would make me laugh after lunch, could fly me into rage before lunch; i know for sure that most human are the same in this regard, some proverbs and some habits, like the habit to treat serious business just after or during dinner, testify). And try lack of air, you bet you will "go crazy for a new dose". These drugs removal is just impossible, you'll die if you try. I guess "kids removal" won't kill a mother outright, but i strongly advise against for the health of the children, the mother, and the person trying the feat (since the mother is likely to get crazy enough to kill if she can). etc. Gem fr (talk) 13:40, 25 July 2017 (UTC)[reply]

Porn, sex, gambling, adrenaline thrill seeking, sport and internet are drug-related, in some way. Or, rather, drug related addictions tap on pleasure and pain chemical systems of our body, and they have no reason to be stronger per se. What drugs are, for sure, is: easier, less time consuming, and not as limited in strength. I mean, to enjoy sensation similar to neurobiological effects of physical exercise aka "runner's high" (for instance), you need either hour-long and physically taxing exercise (and the pleasure will be limited), or a shot of some drug in a matter of seconds, with no exercise, and you can get the dose equivalent you would get by running 1000km or 1 Million km if you want (which you cannot get by running!) .

So, why would morphine be more addictive than an equianalgesic dose of enkephalin or beta-endorphin, produced by the body, all binding to the μ-opioid receptor so that in effect the body is mainly unable to make a difference between them?

Then again, the main difference is in doses, and it makes sense to expect a stronger addiction to stronger doses, doesn't it?

Gem fr (talk) 13:39, 25 July 2017 (UTC)[reply]

Or short Reward system. I have to disagree with Gem fr regarding the doses. Contrary nature even adapts by making frequent usage less rewarding, even when the dosage is risen. Up to states when addicted dont get their "kick" or reward anymore, like eating something you really dont like - but the hunger is gone. You will never feel pain from not getting chocolate or sweets anymore but you will from hard drugs. So hard it will define you completely. Much more even then any grade of hunger or thirst. All these other things you mentioned will not absolutely define you. Thats how i compare them (as not addictive). --Kharon (talk) 22:52, 25 July 2017 (UTC)[reply]

I don't think we disagree. equianalgesic mention the effect of chronic use and tolerance as something to take in consideration (among other factors), as it change effects. Hunger is not a pain, it is ... hunger. Same thing for thirst or love. Even though we usually describe these feeling as being sometime "painful", they use specific biologic systems (see those article), not the pain warning system and hence don't mess with it, as hard drugs do. I am pretty sure chocolate and sweets don't tap on the pain system, either, that's why stopping them shouldn't be painful. Gem fr (talk) 10:30, 26 July 2017 (UTC)[reply]

Anorexia can be like a non-drug addiction, and for a significant percent of those afflicted with it, it can be fatal. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:10, 25 July 2017 (UTC)[reply]