Wikipedia:Reference desk/Archives/Science/2011 May 4

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May 4

Suggestions: seemingly complex process which is simple.

I'll avoid details for now otherwise this will take too long to explain: Traveling at the speed of light seems impossible to us, but it's the most natural thing a photon can do. If you were a photon, traveling at the speed of light would be a piece of cake. I'm using this for an article I'm writing to explain how something like the complexity inside a living cell might seem incomprehensible to us, but the components of each cell are just "going about their business".. I'm after one or two good examples of other processes which might superficially appear to be complex or incomprehensible, but are actually fairly simple reactions. I thought of combustion or salt dissolving in water, but that’s a little too simple. I'd like something that's still common and easy to explain, but has slightly more complex "interactions" happening, maybe something like snow flakes forming.. Avoiding examples directly related to life, like the patterns on flowers and stuff like that. Vespine (talk) 02:35, 4 May 2011 (UTC)

Try photosynthesis maybe? In the gross, fuzzy, zoomed-out picture, photosynthesis is essentially reverse combustion of glucose: 6CO₂ + 6H₂O --> C₆H₁₂O₆ + 6O₂. How the plant acctually causes a reverse combustion, however, is crazy complicated. See Calvin cycle for one little tiny part of photosynthesis; basicly the part where you need to strip the oxygens off of the CO₂. And that's just one little part of it. --Jayron32 04:28, 4 May 2011 (UTC)

Human reproduction is an extremely complex process that even uneducated people manage to perform. Cuddlyable3 (talk) 07:54, 4 May 2011 (UTC)

And that some higly educated people can not. Googlemeister (talk) 13:05, 4 May 2011 (UTC)

[Adding a missing "close small" command to resize following entries.] {The poster formerly known as 87.81.230.195} 90.201.110.64 (talk) 13:12, 4 May 2011 (UTC)

For the purposes of illustration, Conway's Game of Life gives rise to complex phenomena at large scales but has very simple local underlying rules that determine its individual "reactions" at a small scale. Gandalf61 (talk) 09:16, 4 May 2011 (UTC)

Also the Mandlebrot set and various other fractals. Staecker (talk) 21:45, 4 May 2011 (UTC)

How about ants walking in a circle? [1] Aaadddaaammm (talk) 13:20, 4 May 2011 (UTC)

Homing pigeons, bees finding their hive by the sun.. Any Extremeophiles. —Preceding unsigned comment added by 165.212.189.187 (talk) 18:56, 4 May 2011 (UTC)

Thanks for those suggestions but I did say to avoid processes related to life, because, well, I'm trying to use it to explain life.. Conway's game and mandlebrots is close, but they are still difficult to explain to people not familiar with them, i'll have more of a think about them anyway.. I was thinking more of just a chemical reaction that you could say: "some molecules get split up into parts, re-arranged, joined with something else into a complex arrangement, and this happens billion times a second, but all that's happening is **something simple**." Vespine (talk) 00:52, 5 May 2011 (UTC)

How about rain, lightening, hurricanes, ocean waves, or fire and magnets? —Preceding unsigned comment added by 165.212.189.187 (talk) 17:26, 5 May 2011 (UTC)

Lightning! Brilliant, that's exactly what I was after; it even USED to be explained by pleading to the supernatural, I hadn't thought of that angle but it suits perfectly. Cheers! Vespine (talk) 22:54, 5 May 2011 (UTC)

How about the Sun ? The nuclear reactions and magnetic field and corona are all complexly related, but we just think that it "burns" hydrogen, giving off heat and light. StuRat (talk) 06:39, 6 May 2011 (UTC)

An astronomer once said: A gas consisting of hydrogen and helium alone can give rise to humans, cars, cities, computers etc.. All that is involved here are the interactions between atoms and nuclei that are described by a few lines of equations. Count Iblis (talk) 15:33, 7 May 2011 (UTC)

how did the swiss alps form

how did the swiss alps form? I heard on a history channel show that it had something to do with a plate collission between europe and africa. I was asking because i cant seem to find a wikipedia article that completely answers my question. could you help? —Preceding unsigned comment added by 70.240.65.240 (talk) 02:52, 4 May 2011 (UTC)

Geology of the Alps leads to Alpine orogeny (not a terribly informative article, but a start). Clarityfiend (talk) 03:13, 4 May 2011 (UTC)

Not sure how deep into the process the programme you saw went, but there is a little more here: [2] - And a pretty heavy looking piece of research here: [3]

Fault-block mountain formation lists the Alps amongst its examples. Darigan (talk) 11:25, 4 May 2011 (UTC)

The tectonics of the alpine region of Europe are very complicated -- the Italian boot is sort of a microcontinent all its own, with subduction happening on both sides as well as to the north. Looie496 (talk) 16:10, 4 May 2011 (UTC)

The Alps mark the former position of part of the Tethys Ocean. This area of oceanic crust (known as Alp-Tethys) was formed in the early Jurassic as Pangaea began to break up, forming the original northern end of the central Atlantic. A group of microcontinents including Apulia /Adria rifted off from Africa during the late Permian as another part of Tethys (called neotethys) formed (parts of this still exist as the Mediterranean). During the latter part of the Cretaceous Alp-Tethys began to be consumed by subduction as Africa converged on Eurasia. Collision occurred between Apulia/Adria and Eurasia at the end of the Eocene causing the Alps to form. The diagrams in this paper may help make this clearer. Mikenorton (talk) 19:47, 4 May 2011 (UTC)

2001-type centrifugal spacecraft - are they non-starters?

Having seen and marvelled at the gigantic ferris wheel spacecraft in the movie 2001, I assumed that this was how humans would travel in space, with a gravity-simulating centrifuge providing Earth-like conditions. I'm pretty sure everyone else thought so too. Now, decades later, I read of the grave problems associated with long-term exposure to weightlessness, problems that cannot be negated by special exercises. Yet the idea of building the ships as shown in Kubrick's film never gets raised now, not even as suitable craft for long missions to Mars. Why is this? Myles325a (talk) 10:51, 4 May 2011 (UTC)

Too bulky. Which makes it appropriate for larger scale projects. Larger than the international space station. Dauto (talk) 12:05, 4 May 2011 (UTC)

The radius of such a habitat needs to be large enough that the perceived difference in "gravity" between an occupant's head and feet is negligible: balance problems are consequences of a sharp gradient of force over two meters or so, plus problems with Coriolis effect that would induce a lateral acceleration when changing height relative to the floor; motion sickness would be an accompaniment to such movements. I've seen discussions of the (utterly fascinating) setup in Discovery One that indicate that the centrifuge would have to be much larger than depicted for it to work. Acroterion (talk) 12:17, 4 May 2011 (UTC)

Some maths. According to the Artificial_gravity#Rotation article, the maximum speed of rotation is 2 revolutions per minute, or about 0.2 radians per second. To produce 1g of acceleration, according to the centripetal force article at this speed, the station would need to have a radius of 250 metres. — Preceding unsigned comment added by Csmiller (talk • contribs)

I will note in passing that there are proposals on the boards that allow for the use of centrifugal gravity (with a large radius of rotation) in a 'small' spacecraft for a long-term mission to Mars. These proposals envision a small crew compartment joined by a long structural member (either a rigid truss or a flexible tether) to a counterweight mass hundreds or meters away. The entire mass is set rotating, with the truss or tether in tension. Challenges associated with these designs include concerns about the weight of the tether/truss and its deployment system; the ability to reliably deploy and collapse such a system both here and in Mars orbit; the unpleasant consequences of a mechanical failure of the tether (due to undetected manufacturing errors, unanticipated material fatigue, or meteoroid hit); the difficulty of maintaining a constant orientation for communications equipment and scientific instruments; and the difficulty of applying thrust to the entire rotating assembly in a way that does not buckle or snap the long, fragile connection. Here's your retro-looking 1989 NASA artist's conception: [4]. TenOfAllTrades(talk) 13:03, 4 May 2011 (UTC)

Almost all the sci fi spaceships don't have anywhere near the radiation shielding required for 180+ day missions. For anything that long, cosmic rays are very dangerous. There is some question as to whether it would be more economical to launch such shielding or build it in space by welding asteroid fragments with robots; so much is required that the latter may be much less expensive. As for artificial gravity, I agree with TenOfAllTrades. 99.39.5.103 (talk) 16:06, 4 May 2011 (UTC)

The ISS has very little shielding and people stay there for very long periods. There are risks associated with that, but they aren't large enough to stop people going there. --Tango (talk) 22:45, 4 May 2011 (UTC)

The ISS is protected by the Van Allen belt.(ref). Interplanetary spacecraft would not be.(ref) -- Finlay McWalter ☻ Talk 22:58, 4 May 2011 (UTC)

Naturally we have an article. The usual countermeasure envisaged for Mars missions (according to various lectures I've attended at Mars Society conferences) is to incorporate a radiation shelter (probably shielded by the onboard water supply) in the middle of the craft. Cosmic rays arrive randomly but, it's thought/hoped, normally too sparsely to pose an immediate threat, though long-term health effects might have to be accepted as a price worth paying: the greater acute danger is from Solar flare radiation and coronal mass ejections, but these are brief enough and can be observed with enough lead time for the crew to take to the shelter until the hazard has passed. {The poster formerly known as 87.81.230.195} 90.201.110.148 (talk) 07:21, 5 May 2011 (UTC)

Ten's account of an artificial gravity method sounds quite feasible. Artificial gravity could be achieved by extending two parts of the ship on an extendable beam like a pantograph, or by a cable. There could be two habitats diametrically opposite or one habitat counterbalanced by the engine module, with the heavier engine module closer to the center of mass. The greater the distance of the habitat from the center of mass, the slower the rotational speed needed and the less the head to feet gravity gradient. The cable could be reeled in when it was time for deceleration burn. It would not necessarily have to be full Earth gravity to get some benefit. Yes, things would get ugly if the cable snapped. Lots of other failures would also be bad, such as an engine or large liquid oxygen tank blowing up (Apollo 13?), so the possibility of a cable snapping is not a good reason to throw away the physiological and psychological benefits of artificial gravity. Some sci fi accounts of a bicycle wheel space station described it as starting with 2 or 3 modules along the circumference of the wheel, with the remaining segments added over time until the torus is complete. Edison (talk) 19:40, 5 May 2011 (UTC)

A rotating station also presents difficulties in using solar panels, launching or docking ships, and performing exterior maintenance via space walks. One option sometimes proposed is to have a rotating portion and a stationary portion, but then there's the issue of how to connect those. Then there the loss of the advantage of being able to lift heavy objects (albeit slowly, due to the large inertia involved). StuRat (talk) 06:24, 6 May 2011 (UTC)

Are we perpetuating an error on degrees proof?

I was taught at school that gunpowder plus alcohol/water would merrily burn at fairly low concentrations of alcohol but that 100 degrees proof was the concentration of alcohol needed for the gunpowder to explode/flash (or more specifically to combust anaerobically, without needing air). But our article Alcohol proof and elsewhere says that 100 degrees is the amount needed for gunpowder to ignite rather than explode and cites [5] which is a personal page of an academic who is as far as I can tell a computing officer not a chemist. I have spent 25 minutes hunting around the internet to try to find any other sources and all of the ones I can find either directly cite this computing guy (as we do) or cite us. This is not really a very credible source for such a belief, can anyone find anything better? Even QI seems to come back to the same guy but IMHO Christmas Pudding holds a flame with 50 degree proof brandy and I can burn wood ash in brandy (just tried it) so the test must be explosion (or anaerobic ignition) not ignition. Can someone find a proper source? --BozMo talk 12:22, 4 May 2011 (UTC)

[6] or [7] might be a reference worth citing.--Stone --Stone (talk) 14:47, 4 May 2011 (UTC)

What I understand from the older sources is: Mix alcohol with gunpowder then light the mixture then the alcohol burns off at the end the gunpowder ignites or does not ignite. If the alcohol is more than 57% no water is left behind after burning and the gunpowder is dry and ignites, if it is less than 57% water is left behind and the gunpowder does not ignite. --Stone (talk) 16:17, 4 May 2011 (UTC)

Thanks. Okay, but that doesn't sound like a very clear cut test... more like biting a coin that a definite percentage? The alcohol water vapour mix will ignite depending on the temp but below 57% in general and the proportion of water level in the powder must be variable. And is the "ignition" always effectively reacting anaerobically without added air? The second of your references clearly says "explodes"--BozMo talk 17:05, 4 May 2011 (UTC)

It is a very old method and done by English sailors, not the officers, most of those would be not able to do anything different to a very simple method. The method might work if you use the standard English gunpowder and the standard tin spoon of a low ranking sailor in the climate of the English channel at the humidity of a 50 gun ship sleeping quarter. But please have a look at the Monty Python and the Holy Grail scene in which the woman is tested for being a which. --Stone (talk) 18:14, 4 May 2011 (UTC)

Think about it in terms of heat of combustion. Below 57 abv there is not enough energy to heat the gunpowder up to the point it ignites. It might scintillate on the surface but that is not enough to start a runaway burn. The ratio of alcohol to water doesn't change. The V2 rocket had water added to the fuel to prevent the combustion chamber from softening and blowing apart. Once the customs & Excise offices know it is above proof, they can then dilute a sample down in steps to the proof point. Then they know how much above proof the rest of the cask is and tax it accordingly. I think they tax increased by each degree of proof, so it must be within about half a percent of volume. It would not leave the distiler much room to argue. --Aspro (talk) 18:08, 4 May 2011 (UTC)

The heat of combustion must be sufficient to evaporate all the water, if the water is evaporated the gunpowder ignites. If there is still water there when the alcohol flame stops the gunpowder does not ignite.--Stone (talk) 18:18, 4 May 2011 (UTC)

No. If that was the case, one could concentrate alcohol by burning some of it off. Even when the gunpowder does go off, its like a damp squid because it is wet. The taxes on First proof, second proof, etc. is given here for different liquors. Commercial tariffs and regulations, resources, and trade, of the several states of Europe and America: http://books.google.co.uk/books?id=vX0FAAAAQAAJ&pg=PA1413&dq#v Looks like several hours-worth of light bedtime reading to be had in this little gem.--Aspro (talk) 18:32, 4 May 2011 (UTC)

Really it is wet afterwards? You made the experiment yourself? Show a few images! --Stone (talk) 19:19, 4 May 2011 (UTC)

Ethanol and water form an azeotrope at about 191 proof (American reckoning). Below that, if you heat the mixture, the ethanol vaporizes faster than the water, and the ethanol concentration goes down, not up. I don't know why it would be different when it's burning. --Trovatore (talk) 19:24, 4 May 2011 (UTC)

(Just noticed you have a PhD in chemistry, so I'm sure you know more than I do about azeotropes. The argument seems sound to me, though; if not, maybe you can explain why.) --Trovatore (talk) 19:35, 4 May 2011 (UTC)

You ask for a few images! See the The Proof Test http://www.youtube.com/watch?v=pTzcd6D0cTA Four and a half minutes in, he shows a control burn, of just black powder – which is perfectly dry. See the difference? Also, if water could evaporated off in preference to the alcohol -as you suggest it can- then then why doesn't the process of distillation work back to front from the way it does? The wort is left in the still (where the heat is added) and the liquor (alcohol) ends up in the receiver -not the other way around. --Aspro (talk) 21:44, 4 May 2011 (UTC)

I look at the process more in a way of absolute energy than in a way of a distillation, which is not true due to the problem with the high temperatures at the surface of the liquid an later with the wick effect when most of the liquid is burned away. The distillation requires the certain concentrations in the gas phase above the liquid and I do not have the slightest clue if this is still true in a flame. So the energy produced by the flame must be enough to evaporate the alcohol and the water this might be the case at the 57%. --Stone (talk) 10:58, 5 May 2011 (UTC)

A better video might be this one. [8] --Stone (talk) 11:34, 5 May 2011 (UTC)

Hey! I suggest the op should look in terms of absolute energy first. Stop trying to shift position. Remember, the OP posted a question here for the purposes of getting clarity on the proofing article. Your fun video of some guys larking about is fun, but what has that got to do with real proofing? If you can come up with a clear way of explain the chemical process of proofing alcohol, then please do so, but don't try to confuse matters with light-hearted You tube uploads. --Aspro (talk) 22:58, 8 May 2011 (UTC)

Scent glands in cattle

Sheep have scent glands on their faces and between their fingers. Do cattle also have these glands? What other "remarkable" scent glands do cattle have? Thanks. Leptictidium (mt) 12:32, 4 May 2011 (UTC)

What do you mean by between their fingers? Neither sheep nor cattle have fingers. Googlemeister (talk) 12:58, 4 May 2011 (UTC)

Well, they're all Even-toed ungulates, so their digits are conventionally toes not fingers, but otherwise the OP's intent is evident. The article Territory (animal) mentions that "many ungulates, for example the Blue Wildebeest, use scent marking from two glands, the preorbital [facial] gland and a scent gland in the hoof": the Muskox is actually named for the males' facial scent glands (or the smell eminating therefrom). Those species belong to the sub-families Alcelaphinae and Caprinae respectively, which are sister sub-families of the sub-family Bovinae to which Cattle in the conventional sense belong, under the umbrella of Family Bovidae. I haven't been able to trace any references to scent glands specifically in cattle, but "absence of evidence is not evidence of absence", and someone else may know better. {The poster formerly known as 87.81.230.195} 90.201.110.64 (talk) 13:19, 4 May 2011 (UTC)

Specific heat capacity (Cp) for a Ni/α-Al2O catalyst

Hello. I need to find the specific heat capacity (Cp) for a Ni/α-Al2O catalyst. It is a catalyst used in steam reforming of methane, as can be seen at this link.

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFJ-42JYWV9-11&_user=559483&_coverDate=03%2F15%2F2001&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1740042659&_rerunOrigin=google&_acct=C000028178&_version=1&_urlVersion=0&_userid=559483&md5=13835dcd75ff9b8d295423d1947c17e3&searchtype=a

Any help is appreciated. If there are no exact values, methods for approximating the specific heat capactiy would be greatly appreciated.

Thanks in advance for the help guys =)

Cuban Cigar (talk) 12:45, 4 May 2011 (UTC)

Can anyone identify what kind of gemstone this is?

Thanks in advance. Sεrvιεи | T@lk page 15:09, 4 May 2011 (UTC)

My best guess is turquoise. It doesn't look as translucent as jade, nor does it seem to have the iridescence of opal. -- 140.142.20.229 (talk) 17:44, 4 May 2011 (UTC)

My thought was lapis lazuli. --Trovatore (talk) 17:54, 4 May 2011 (UTC)

To me it looks too blue to be turquoise. Are you sure it's a gemstone, and not just something like sodalite? Wnt (talk) 22:10, 4 May 2011 (UTC)

Excuse my ignorance, but checking out the linked articles, it appears that sodalite is a gemstone and a common component of lapiz lazuli. DRosenbach ^{(Talk | Contribs)} 23:34, 4 May 2011 (UTC)

Wow. You're right that's what the article says. I didn't imagine something with hardness 5.5-6 could be a gem! Wnt (talk) 06:10, 5 May 2011 (UTC)

I had better advertise my article on trisulfur radical anion which gives the blue colour. Graeme Bartlett (talk) 09:17, 5 May 2011 (UTC)

In sodalite, you mean. The main blue in lapis (are we all agreed that the stone in the picture is lapis lazuli?) is apparently lazurite, which doesn't have a trisulfur. --Trovatore (talk) 00:08, 6 May 2011 (UTC)

Oops, guess I misread that. The article says it does have a trisulfur. I didn't see it in the chemical formula, which is what led me astray. --Trovatore (talk) 01:08, 6 May 2011 (UTC)

High sodium diet protects against heart disease?

The result of this study is that there is no link between heart disease and salt intake. However, the details are that:

Findings revealed that those having the lowest levels of sodium, an average of about 2,500 mg, or a little more than one teaspoon daily, gained no benefit in reduction of risk against development of high blood pressure than those who had the highest levels of sodium at an average of nearly 6,000 mg per day. In fact, heart disease deaths were reduced with higher sodium intake, as 50 deaths occurred among the one-third of the participants having the lowest sodium intakes, while there were only 24 deaths among those with average intakes, and just 10 deaths occurred among those with the highest sodium intakes.

And this suggests that there actually does exist a relation between heart disease and salt intake. Count Iblis (talk) 20:53, 4 May 2011 (UTC)

Note that "Many randomized trials have shown that an increase in potassium intake lowers blood pressure (BP), particularly in individuals with raised BP." ^[9] It's my personal opinion - but I'm not aware of any substantiation in scientific study - that the "hunger for salt" can lead a person to using excess sodium salt when what is actually craved is potassium. Wnt (talk) 22:19, 4 May 2011 (UTC)

What's the question? In the article I read, it only suggests that cutting sodium for a young person is worse for you, and not that there is no link at all. --Wirbelwindヴィルヴェルヴィント (talk) 22:21, 4 May 2011 (UTC)

It is still being summarized as: "no link between sodium intake and heart disease", which I find strange. Count Iblis (talk) 22:24, 4 May 2011 (UTC)

Are you complaining about the abstract of the study OR the news report? Since there's no link to the study here, I'm guessing the later. News reports are notorious for making misleading or downright false claims about studies and that's highly reliable sources. I don't think there's much point discussing how some random report, which from the look and name of (and absence of any wikipedia article for) the site, isn't even appearing in a WP:RS is wrong (presuming it is, as I've said I haven't looked at the actual study nor did I bother with the news report so I have no idea). Nil Einne (talk) 22:59, 4 May 2011 (UTC)

This is the paper in question. The news report appears to be pretty accurate, except that it talks about sodium consumption whereas the paper looks at sodium excretion. Looie496 (talk) 00:45, 5 May 2011 (UTC)

In fact looking in to this more, I'm even more confused by the question. The above "no link between sodium intake and heart disease" which given it is in quotations marks most people would presume is a direct quote doesn't appear in the news report nor are there any Google or Bing results for that precise phrase. Having actual read the news report, it doesn't in any way suggest "that there is no link between heart disease and salt intake" as the OP said in the first post or the similar quote that isn't a quote so it's even more perplexing why the OP thinks the research is summarised so. It's possible the article has changed since the OP read it, sadly a not uncommon problem with online news reports otherwise I remain perplexed. If this is something to do with a wikipedia article, this should be dealt with in the talk page (where I suspect it would easily be resolved) and this should have been made clear at the beginning. Nil Einne (talk) 02:09, 5 May 2011 (UTC)

That's partially what I was trying to say earlier. OP might have seen a bad report or headline on it. I personally think this article from CNN is a little more clear. --Wirbelwindヴィルヴェルヴィント (talk) 03:30, 5 May 2011 (UTC)

That CNN article seemed to have a bit of fun, by calling the analysis of sodium excreted in urine the "gold" standard. :-) StuRat (talk) 06:07, 6 May 2011 (UTC)

The paper abstract says "Lower sodium excretion was associated with higher CVD mortality." So, if you are poor at excreting excess sodium, then you have more chance of heart disease. That is entirely consistent with the most recent dogma that too much salt is harmful. Why the fuss? It is certainly NOT suggesting that a high-salt diet is good for you. 92.28.243.102 (talk) 11:27, 6 May 2011 (UTC)

Other news reports I've seen later do write that more salt can be better. Thinking more about this, I think there is something strange going on. The inferred salt intake in the group with the lowest amount of salt excretion is very low. So, these must be healthy 40 year olds who eat very little. Perhaps this is then the cause. A healthy person like me who exercises a lot will eat a lot of bread and then the salt intake will then necessarily be much higher than what is regarded to be safe for heart patients.

One slice of bread containing 80 Kcal contains 0.4 grams of salt. I eat about 15 slices of bread per day, so I get 6 grams of salt from my bread meals only and that then only from the dry bread. Add to that the salt in cheese, meat and the salt in the food I eat for dinner and you get to perhaps 12 grams of salt per day. This is then despite me sticking to the most stringent guidelines to limit salt intake as much as possible (I don't add any salt to my food, I almost never eat ready-made foods like pizzas etc. etc.). Count Iblis (talk) 15:21, 6 May 2011 (UTC)

I don't think any disputed that the study appears to show more salt could be be better. Your first comments did not appear to be questioning that point and I think we're still not sure what you were referring to but I guess it doesn't matter. The study authors have suggested people not read too much in to this study which is a different thing and understandable.

I'm not sure why you believe a healthy person who exercises a lot will eat a lot of bread. There are plenty of diets even for those who are highly physically active, many them don't involve consumption of a lot of bread (I'm not saying it's bad for you, you'll need to consult a medical professional for that but I'll be honest 15 slices of bread a day everyday seems like a lot to me although perhaps you're built like a rugby player).

Also your figures are confusing since you are talking about salt but the study talked about sodium. According to our article, in the UK the Reference Nutrient Intake 4 g salt per day which is 1.6 g of sodium. (I'm presuming that is accurate, I'm lazy to work it out myself.) The recommended upper limit varies depending on country but tends to be around 2300 mg of sodium which would be 5750 mg of salt. A meta-analysis showed the sodium consumption in 33 countries fit in the 2,700 to 4,900 mg/day range. The maximum intake of the study was 6000 mg of sodium (15g of salt), somewhat above the average range in other words clearly not average. If you are really getting 12gm of sodium then you are well, well above both the average intake and that in the study and so I wouldn't read anything in to it. If you are getting 12gm of salt and therefore ~4.8g of sodium you are within the average range and below the maximum in the study. :Nil Einne (talk) 17:00, 6 May 2011 (UTC)

Thanks, I'll look into the salt content of bread to see if the figure I found refers to sodium or salt. About eating bread: you can easily carry it with you and eat it wherever and whenever you feel like eating. Count Iblis (talk) 21:40, 6 May 2011 (UTC)