Wikipedia:Reference desk/Archives/Science/2013 September 20

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September 20

Weekly medicines

I'm back from the pharmacy, and the pills that I'm going to take are to be taken weekly. This surprised me a bit, as most medicines I've taken before are taken daily or twice a day. Granted, I don't know much about how these things work, but intuitively, my understandig of a drug that's taken frequently is: the drug enters the body, passes through the system and is then either 'used up' or disposed off (e.g. through urination). But how does this work for a drug that's taken weekly? I.e. how is the drug as effective a week after being taken compared to right after it's been taken? 168.120.4.239 (talk) 02:20, 20 September 2013 (UTC)

There's a trend toward taking longer acting drugs, since the patient is more medically compliant the fewer doses they take. Certain antibiotic pills like zithromax are like this now, each pill lasting for several days, with a five-day course of six pills having effect for quite a while after the last pill is taken. Metabolic half life can vary greatly. Slow acting fat-soluble hormone pills can be effective for quite a while. Exenatide for blood sugar is long lasting, and has a form that can be given weekly--good if you are perhaps senile and get home nurse visits weekly. There are myriad reasons and mechanisms. A drug may effect a condition that takes some time to reach a state that needs addressing (see IP 121's answer below on chemo and cell division). There are osteoporosis pills that are given twice a year if their effects can be tolerated, but in smaller and more frequent doses by the less tolerant. A specific explanation would need the name of a specfic drug--you should look up our articles and check the stats on their metabolism. μηδείς (talk) 02:47, 20 September 2013 (UTC)

There are also certain meications for which a high dose weekly schedule produces less side effects than a low dose daily schedule. Our article on methotrexate merely says that it is dosed weekly rather than daily, but when I was prescribed it, I was told by my doctor that this was the reason. MChesterMC (talk) 09:30, 20 September 2013 (UTC)

Why would this effect exist ? If anything, I'd expect a higher dosage at one point in the cycle from a weekly drug than a daily one (at 1/7th the dosage). StuRat (talk) 10:59, 20 September 2013 (UTC)

Chemotherapy drugs, of which methotrexate is a archtypical example and one of the oldest cancer chemo drugs, act by wrecking cell processes during division. Depending on the type of cancer, the drug is given at intervals of either two or three weeks. The idea is the a dose is given and many cells (cancerous or not, but division is a high probability in cancer cells) that are in the process of dividing are stuffed up and die. Cells that are not in the process of dividing (again, cancerous or not) are not affected. Within a few hours of receiving the drug, almost all of it is excreted in urine. The body is then left with cells that will want to divide sometime in the next 2 or 3 weeks, with the probability of cancer cells getting ready to divide rising over that 2 or 3 week period. About 2 or 3 weeks later, a maximum of remaining cancer cells are ready to divide again, so you hit them with another dose. The dividing cells then die, and you are then left with unaffected cancer cells wanting to divide 2 or 3 weeks later. So, 2 or 3 weeks later, hit them again. The cancer is driven into a cycle - just as like a boxer getting up again, you hit them hard at their worst time. Giving the drug more frequently will not be effective, as less cancer cells will be ready to divide. It would however, kill blood cell production. Giving the drug on a 3 week cycle allows the production of blood cells to continue at something somewhat less than the normal continuous rate, being interrupted for a while every 2 or 3 weeks, which the patient can tolerate. Chemo is almost always used for breast cancer, as breast cancer cells divide frequently. Chemo is not much used for prostate cancer, as prostate cancer cells (usually) divide infrequently and it is hard to drive them into "hit when they are down" cycling.

We don't know what Chester was prescribed methrotrexate for. It is used for other purposes beside chemotherapy for cancer, e.g., Crohn's, psoariasis. The approach my be different for these uses.121.215.11.211 (talk) 15:08, 20 September 2013 (UTC)

I am not sure if I read the methotrexate article correctly, but it seemed like weekly doses were safer than daily doses which might be taken too quickly together or be misadminitered if taken intravenously. Basically fewer chances for a life-threatening mistake. μηδείς (talk) 17:24, 20 September 2013 (UTC)

It's for the reasons I gave, and normally for most cancers 2 to 3 weeks, not weekly. If you attempted to give methotrexate as chemotherapy for cancer more frequently, you would reduce blood white cell count risking disease and death from infections, without killing many cancer cells, because it only kills cells that are dividing. For treating things like Crohn's, the mechanism for treatment is different (the idea is to partly cripple the immune system) and much lower dosages would be used, so safety comes with the lower dose, which can be more frequent. When methotrexate and similar drugs are used as cancer chemotherapy, hospitals use a number of special checks to ensure the dose is correct, and records kept & the whole procedure makes getting another dose too early extremely unlikely. But the risks if a high dose is given in error are not that bad. Just because you can't make any new red or white cells for a couple of days, you won't die - you should already have plenty in circulation. You might be a bit thick (so called "chemo brain") on learning new tasks or subjects as your brain won't be able to make new cells either. 124.182.5.71 (talk) 01:18, 21 September 2013 (UTC)

• For the OP. If you are interested in this topic generally, see Pharmacokinetics especially the "LADME" acronym which deals with the manner in which a drug is processed by the body. Pharmacokinetics looks, among other things, into how long it takes for a drug to enter and then pass out of the system, how long its effects last, etc. Based on the particular pharmacokinetic properties of a particular pill will determine how long between doses. --Jayron32 17:31, 20 September 2013 (UTC)

... and in addition to pharmacokinectics, one would also need to know the drug's margin of safety (redlink!), which is (roughly) the ratio of its lethal dose to its therapeutic dose. So for example, even if two drugs have the exact same pharmacokinectics, one could be prescribed a higher (and less frequent) dose of the one with the larger safety margin, since the body could tolerate the resultant higher peak concentrations. Abecedare (talk) 18:14, 20 September 2013 (UTC)

It depends on the drug, but something like Fosamax is taken weekly because it isn't circulating free in the serum but incorporated into the bone. There is a much more familiar drug that works a bit like this -- sodium fluoride, treatment with which during childhood is believed to affect dental health for many years. Wnt (talk) 18:02, 20 September 2013 (UTC)

Some drugs act in such as way that the effect doesn't change much with concentration in the body. For example, Xarelto, used to reduce the risk of strokes caused by blood clots in people with fauly heart valves or atrial fibrillation, has an effect roughly proportional to blood concentration up to a certain level, and beyond that concentration the effect levels off. This means that the effect stays roughly constant while the blood concentration is reducing over time since the last dose. So patients are told to take the next dose at the end of the plataeu time. 124.182.5.71 (talk) 01:18, 21 September 2013 (UTC)

Which is the most intelligent insect?

I'm really interested in insects with individual intelligence, not colony insects. I'd personally have assumed that the preying mantises (manti?) would be contenders for most intelligent insect. I've read pet mantis owners saying that they can learn recognise individual humans and can be trained, but I'm not 100% sure if that's true or not. --146.90.70.130 (talk) 12:24, 20 September 2013 (UTC)

It's hard to tell, because we can't get any of them to hold a pencil well enough to take the WAIS-IV. --Jayron32 13:41, 20 September 2013 (UTC)

Yes, first you'd have to define what intelligence means for an insect. I don't think anyone's bothered yet. HiLo48 (talk) 14:25, 20 September 2013 (UTC)

Please don't guess at answers. There are whole books and journals devoted to similar topics. SemanticMantis (talk) 14:35, 20 September 2013 (UTC)

It's hard to eliminate social insects in that. Honey bees have about a million neurons compared to a fruit fly's hundred thousand. There's probably a lot of that involved in social interactions. Dmcq (talk) 14:32, 20 September 2013 (UTC)

There are lots of caveats, e.g. how to define intelligence, how to compare intelligence, etc. That being said, insects can learn, and can display complex behaviors, and some can learn different things, or learn faster, than others. You aren't interested in social insects, but solitary bees and solitary wasps can generally learn quite a bit, how to navigate, find landmarks, get food from different sources, etc. Basically, many of the things you can train honey bees to do, you can train (some) solitary bees to do. As a general principle, we'd expect top predators to need more intelligent behavior than most herbivores. Mantids (plural of mantis is mantids or mantises) fit the bill, and also the dragon flies. You can google and find lots of sites describing how to care and train mantids. Dragon flies can "hover" in a breeze without flapping their wings, that takes some serious sensory feedback and brain power.

For more refs, here's a whole book on insect learning [1], and here's a nice review article [2].

I know you said insect, but if you are interested in smart arthropods more generally, check out the Portia_(genus) of jumping spiders. They have very complex hunting behavior and spatial reasoning, they can see prey, leave visual contact, then loop around to ambush. This type of hunting is commonly associated with e.g. lions, and much bigger-brained vertebrates! You can catch salticids in most parts of the world, I highly recommend playing with some, their intelligence is (to me) almost palpable! SemanticMantis (talk) 14:35, 20 September 2013 (UTC)

"Dragon flies can "hover" in a breeze without flapping their wings" - is that possible, even in principle? I don't see how. When all of the air is moving around them, there is no frame of reference for "the ground" - so all of their motion is relative to the air flow. From that perspective, why wouldn't they just drop out of the sky? This is more a matter of thermodynamics than brain power or aerodynamics! If there were some means for this to be possible (eg if they had something to hold on to - like a kite has a string) - then it's rather trivial to orient wings at a dihedral angle and be stable in the airflow...kites do it with no brain cells at all! No, I have to call "bullshit" on that one! SteveBaker (talk) 18:06, 20 September 2013 (UTC)

Are you calling BS on dragonflies hovering in an air flow without flapping - or the ability to hover in an airflow without flapping in general? Because I'm pretty sure that gulls can do the latter. They can 'hang' in a certain spot, only by making what would appear to be minute movements of their (spread) wings, but certainly with no flapping, as such. Feed a gull somewhere like the edge of a cliff or on the end of a pier (throw bread to one that's already hovering - because they seem to like hanging out and doing that in these areas anyway) and you'll probably see what I mean. Though I may be missing something here... --Kurt Shaped Box (talk) 22:19, 20 September 2013 (UTC)

In both of those cases, the gulls are able to make use of slope-lift. In strictly aerodynamic terms, in order to create a lift force to counter gravity - you must also create a drag force - and that's going to blow you downwind - so you can't hover. In slope lift, the airflow itself has an upwards component. But in straight-line wind over a level surface - I don't think it's possible to hover without inputting some energy somewhere. SteveBaker (talk) 04:37, 21 September 2013 (UTC)

SteveBaker and Kurt Shaped Box (I ping you because this thread is a little stale) dragonflies can indeed hang nearly stationary in the air, much like gulls do, without any gross flapping motions. In both cases, they do make small adjustments to to their wings, and keep in mind that for dragonflies, very complex flows can be created with four wings that can be positioned in a wide variety of configurations. For a visual example, see e.g. this video [3]. I've seen better examples in real life, but that's the best I could find on youtube without too much hassle. I count maybe one big flap in the whole 19 seconds, the rest of the movements are just sort of "snapping" into different relatively fixed positions. I didn't really mean to debate the semantics of "flap" or "hover", and I think you'll agree this is pretty amazing, no matter what we call it :) SemanticMantis (talk) 01:01, 23 September 2013 (UTC)

One flap every 19 seconds isn't "without flapping" - it's "without flapping very often". The point is that there has to be some kind of energy input...and once every 19 seconds is quite believable. But without flapping at all, there is no possible way for a heavier-than-air insect to stay up there without some kind of a tether in a simple straight-line airflow. SteveBaker (talk) 02:31, 23 September 2013 (UTC)

Or did the dragonfly only flap because it was ready to move on? :) BTW, thanks for the reply to my point about the gulls. I've got a terrible habit of reading these things and then going to do something else and forgetting to acknowledge it... Bridges are another place where you can see floaty gulls. I'd imagine that other birds can do the same, but gulls are quite conspicuous. --Kurt Shaped Box (talk) 06:46, 23 September 2013 (UTC)

We can't really agree on what intelligence means in humans, and with animals much closer to humans than insects, dogs, our article Dog intelligence highlights some of the problems. Some argue that the easily trained, obedient dogs are most intelligent. Others point out that such traits in humans would be seen as seriously problematic. HiLo48 (talk) 14:43, 20 September 2013 (UTC)

Yes, you are right, there are problems with various definitions. But rather than say "there are problems with definitions, I cannot give any answers", I've decided to post good scientific refs, and point the OP toward the better-defined concepts of learning and behavior. You are right that "most intelligent insect" cannot be firmly established, for a variety of reasons. But there are lots of very "smart" insects out there, and lots of research into insect learning and behavior. I think that information will be helpful to the OP. SemanticMantis (talk) 14:51, 20 September 2013 (UTC)

The folk that consider that easily trained dogs, like poodles, are the most intelligent, have not experienced the truely intelligent breeds like Australian cattle dogs or German Sheperds. It is harder to train German Sheperds because they are smart enough to think "why should I sit when you say "sit" - I've done it twice for you today already - sheesh!" And they train you. I trained my Germans Sheperd to jump high in the air to retrieve a tennis ball suspended from a clothes line. She can do almost 3 metres. I have set the height at 2 m, increasing it 100 mm or so until it appeared she couldn't manage it. At 2.6 m, she looked at the ball, looked at me, looked at the ball again, made two leaps not quite making it, and howled as in frustration. Recalling that she managed greater heights a few months before, I cranked the height to 2.8 m and then gone inside the house. 10 minutes later the children who lived next door came home from school. The dog made one single leap, got the tennis ball, and took it over to the children. That is the mark of true intelligence - she tried to trick me, with her very good acting, and she nearly succeeded. 121.215.11.211 (talk) 15:35, 20 September 2013 (UTC)

It seems to me you could just use some of the brute force methods that are currently being used to study the mouse brain. You can take an insect brain, slice it up into a nanometer thin slices, scan all these slices and then reconstruct the structure of the neural network. In case of the mouse brain they will do this for only a fraction of a cubic millimeter of brain matter. Once you have the exact digital representation of such a brain, you can simulate how it behaves using a supercomputer. Count Iblis (talk) 16:51, 20 September 2013 (UTC)

Once you've sliced an insect's brain up it won't be all that smart. HiLo48 (talk) 21:48, 20 September 2013 (UTC)

Ants are widely said to have the largest brain/body ratio; however, this seems to be confined to the optic lobes as a matter of vision. (PMID 2720368) Of course, as we know from human development, changes in brain size can be subtle even when there are enormous changes in intelligence. As one of the first replies alluded, it will not be easy to evaluate insect intelligence based on behavior, due to a lack of obvious standard activities they all do that require mental effort. Wnt (talk) 17:58, 20 September 2013 (UTC)

Ants are colonial (see the OP's question), boring, and follow fixed action patterns. μηδείς (talk) 21:51, 20 September 2013 (UTC)

• My first thought on reading this was Bumblebee! and google confirms it. μηδείς (talk) 21:49, 20 September 2013 (UTC)

Well, it has to be the bumble bee, apparently it had the intelligence to outsmart aerodynamics. Aerodynamics couldn't stop it from flying. Plasmic Physics (talk) 05:36, 21 September 2013 (UTC)

There may be something to that idea - I imagine managing flight using dynamic stall at each wingbeat might take some extra brainpower? But they are also social, so if we're excluding them (rather than just not evaluating colony intelligence) we might want to look at various solitary wasps. (Yellow jackets are also said to be intelligent [4] but are also colonial) See [5], a charming naturalist narrative which singles out Ammophila (wasp). I understand the argument that insect behavior is part of a simple, inflexible pre-program, but I wonder if humans really do so much better when abducted by aliens for tests. Wnt (talk) 14:54, 22 September 2013 (UTC)

The individual bumble bee seems pretty flexible, regardless of the hive intelligence. I took the OP's prohibition as applying to the colony, not the member as members. That being said, the bumble bee article says they exhibit flower constancy, repeatedly visiting only the same plant so long as it produces, and this may indicate another fixed action pattern, rather than intelligent learning. μηδείς (talk) 15:53, 22 September 2013 (UTC)

I suppose that human farmers who repeatedly harvest from one or a few fields rather more fertile fields they drive past on the way are also displaying cognitive limitation. :) Seriously, I don't know, and neither do these authors [6] but I'm not convinced it proves low intelligence. Wnt (talk) 20:51, 22 September 2013 (UTC)

It doesn't prove low intelligence. But fixed action patterns are often mistaken for intelligence, which they are not. Mother wasps don't learn how to sting and bury prey for their young. They just have complex fixed action patterns that achieve that effect. Interrupt them and they will restart their actions without realizing they have already accomplished that goal. If that is the case with bumble bee nectar gathering it doesn't speak well for their intelligence. Indeed, if we define intelligence as learning, the question is very open, and if we define it as creativity, only animals like crows and apes are known to possess it in the area of creating tools. We have a large article, animal intelligence. μηδείς (talk) 21:31, 22 September 2013 (UTC)

The limiting factors on humans, generally speaking, don't have to do with intelligence, but rather with resource limitations. I do find it funny that dogs are rated intelligent if they can be easily trained to obey orders. I don't think that's regarded as the first criterion of intelligence in humans. I hope not, anyway. :( ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:08, 22 September 2013 (UTC)

Training dogs to work is more a question of our intelligence as applied to their capabilities. Hunting using trackers, pointers, flushers, and retrievers is based on the dog's natural capacities as a wolf, interrupted (the dog is capable of enough self control to point without then chasing, or retrieve without then eating) and redirected by our intelligence to our purpose. That's basically the same unskiled labor as working a cash register in humans--handling the money without pocketing it.

Training dogs to do tricks is like teaching children to do tasks like tying their shoes. There's nothing obvious about shoelaces that metaphysically directs us to want to tie them. We can learn the arbitrary (to the child) sequence of doing so if we are praised. The stimulus is external, unlike trying to eat something that smells and tastes good, which children (and dogs) will do if left to their own devices. μηδείς (talk) 22:24, 22 September 2013 (UTC)

According to this source there were "there were birds in the sky". Bus stop (talk) 23:00, 22 September 2013 (UTC)

You may be confused, Bus Stop, I think you meant to say... μηδείς (talk) 01:41, 23 September 2013 (UTC)

Well of course I am confused. I'm hoping that insects are intelligent. Why wouldn't I want an intelligent salticid? At least if this guy is called Four eyes we will know why. Bus stop (talk) 23:35, 23 September 2013 (UTC)

Training dogs to do tricks like "beg", "sit", etc is indeed just a sequence that the dog learns to get praise or food - and requires little inteligence on the part of the dog. Stupid breeds like poodles and spaniels do well at it. But there are other sorts of training. In the training of guide dogs for the blind, the more truely intelligent breeds like labradors are used - poodles and spaniels, which do simple tricks well, just can't cut it. Guidedogs are trained to look at obstacles from the point of view of the human, and make decisions. For instance, that low tree branch hanging over the foot path - from the dog's point of view it matters not a whit - he can just go under it. But the human will hit it. Dog makes a series of decisions: Is branch too low for human, need human to duck? Or is it ok - just keep walking? Go around? Stop until road traffic is safe and take human off footpath (signal human about that deep gutter) to get around obstacle? Or stop and get human to make decision? This is a severe test of intelligence, as a) it requires the dog to evaluate things form the human's point of view, not the dog's, and b) it requires on the spot decisions, not just a pre-programmed sequence. Labradors can do it well. Poodles cannot. A somewhat similar requirement mental flexibility is required of police dogs, which are usually German Shepards, which many in the dog show set regard as stupid, as they get bored with simple pre-learnt tricks. 120.145.70.130 (talk) 03:09, 23 September 2013 (UTC)

wasp and spiders

I’m not sure if this count, but this little blue wasp managed itself very well to literally kill and abduct this big spider of arguably three or four times its body weight, here in Cuba this wasps are very common. If they are not intelligent then they are really bold…

In the middle of the “fight” the spider tried to bite it several times, and I disturbed it with my flash too, but the wasp neither start over again nor leave the poor spider alone, it just keep trying different ways to engage its target… it’s funny, at first the wasp fly an land almost in front of me and stand for a moment staring at me moving its orange antennas like saying: hey! this is mine… get out!! :)

Iskánder Vigoa Pérez (talk) 04:08, 24 September 2013 (UTC)

Do we need to eat saturated fat?

Can saturated fat be left out of the diet altogether or is there a minimum amount we need to eat? Count Iblis (talk) 20:36, 20 September 2013 (UTC)

The only essential fats are those involved in child development. So the answer depends on the questioners age, and since it is impolite to ask you your age, I recommend you seek the opinion of a medical doctor or equivalently competent authority on the subject. Tim AFS (talk) 20:40, 20 September 2013 (UTC)

Essential fatty acid. μηδείς (talk) 21:46, 20 September 2013 (UTC)

I stand corrected. Thank you. Tim AFS (talk) 05:29, 21 September 2013 (UTC)

Thank you. It was not my goal personally to correct you, and I appreciate the polite response. μηδείς (talk) 01:44, 22 September 2013 (UTC)

The only known essential fatty acids are alpha-linolenic acid and linoleic acid, neither of which is saturated. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 23:16, 20 September 2013 (UTC)

There is not a minimum amount of saturated fat we need to eat. Although there are good arguments made to include some saturated fats in your diet (see references), the FDA website says to choose the foods with the lowest amount of saturated and trans fat. http://www.fda.gov/food/ingredientspackaginglabeling/labelingnutrition/ucm274590.htm, http://www.hsph.harvard.edu/nutritionsource/fats-full-story/, http://www.fourhourworkweek.com/blog/2009/06/06/saturated-fat/ Bradbchnn (talk) 01:41, 21 September 2013 (UTC)

Thanks! Count Iblis (talk) 00:44, 22 September 2013 (UTC)

I strongly doubt this question can be answered. Saturated fats are essentially universal in nature, in plants and animals - there are many things that are low in them but I can't think of a living thing you can eat that contains none at all. So in order to test the effect of omitting all saturated fats in humans you'd need to feed people a highly artificial diet, which may be viewed as an experiment that is unsafe and unethical to carry out long enough to see the long-term effects. Wnt (talk) 15:00, 22 September 2013 (UTC)

The experiment would be done if there were a person with a metabolic defect who could not metabolize such fats, and who had to have a special diet or die from such a disease, along the lines of Lorenzo's Oil. μηδείς (talk) 22:27, 22 September 2013 (UTC)

There are many extreme veganist dieters, e.g. Bill Clinton and Angelina Jolie. Count Iblis (talk) 17:24, 23 September 2013 (UTC)

Harvesting power from the oceans?

http://www.intpowertechcorp.com/ has amazing ideas (check out the ~10 minute video) but would it be more practical just to drop anchor and produce power from a http://www.makanipower.com/home/ turbine? Tim AFS (talk) 20:37, 20 September 2013 (UTC)

That depends on whether you want to use the power for ship propulsion or for electricity generation. Note, however, that both these devices create a potential hazard to aircraft. 24.23.196.85 (talk) 22:58, 20 September 2013 (UTC)

Makani says they have aircraft hazard indication transmitters and stay below 1000 feet. I'm not sure the answer depends on the ultimate use of the energy produced. Tim AFS (talk) 05:32, 21 September 2013 (UTC)

Of course it does -- if you want to generate electricity, the Makani device would be more efficient, as you correctly suspected (it converts wind power to electricity in two steps, whereas the INT device requires three steps, hence the better efficiency), but if you want ship propulsion, then the INT device will be more efficient (one-step conversion of wind to kinetic energy, whereas the Makani takes three steps). 24.23.196.85 (talk) 21:14, 21 September 2013 (UTC)

Notung vs. Excalibur

(This is tangentially related to the discussion "Sword made of precious metals") Suppose two Dark Age warriors get into a duel -- one being armed with a Celtic/Anglo-Saxon sword, and the other with a Teutonic/Viking sword. Which of them would have the advantage in the fight? 24.23.196.85 (talk) 23:11, 20 September 2013 (UTC)

Which warrior is the better swordsman in general? ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:28, 21 September 2013 (UTC)

Too many unknowns really. Which is longer? Lighter? Sharper? (Each article says its sword could cut metal.) Clarityfiend (talk) 07:14, 21 September 2013 (UTC)

Nothung is better than Excalibur, Nothung. Of course, you should take that with a Gram of salt. Clarityfiend (talk) 07:10, 21 September 2013 (UTC)

If I recall correctly, Nothung was forged by Siegfried, while Excalibur was forged by the gods (presumably) and its caretaker was the Lady of the Lake. I would go with the one made by the hands of superior beings. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:11, 21 September 2013 (UTC)

And if I recall correctly, Nothung was originally forged by the gods and given to Siegmund by Wotan, and then reforged by Siegfried after it shattered on Wotan's spear. So in fact, both these swords were made by superior beings. 24.23.196.85 (talk) 20:34, 21 September 2013 (UTC)

• A lot depends on the quality of the swords. Smiths in those days had great difficulty forging swords that were not brittle and hence easily breakable -- that's why really high-quality swords were such notable objects. The best material at that time was probably Damascus steel, but it wasn't available in Europe. Looie496 (talk) 15:38, 21 September 2013 (UTC)

The Varangians (Vikings) had access to Constantinople, a major trading hub. Damascus steel was likely available there.--Auric talk 16:00, 21 September 2013 (UTC)

In the Dark Ages (5th century AD), it's unlikely that the Vikings already had access to Damascus steel -- so the more likely material for their swords would be plain high-carbon steel (most likely high-quality 1090 or 1095 steel). But they did have access to advanced (for their time) bladesmithing techniques, including differential tempering and pattern welding, which would have allowed them to make their swords ultra-strong without sacrificing toughness. 24.23.196.85 (talk) 20:34, 21 September 2013 (UTC)

Does eating chlorophyll help the production of hemoglobin?

chlorophyll a

Heme b

Just read a newspaper ad says "Chlorophyll's structure is similar to that of a hemoglobin, and hemoglobin is used to make red blood cells, which delivers oxygen in the body; so chlorophyll helps increasing red blood cells, and is beneficial to human body".Is this accurate?--朝鲜的轮子 (talk) 23:41, 20 September 2013 (UTC)

Heme molecule, to start with. Interesting question. μηδείς (talk) 23:51, 20 September 2013 (UTC)

Prob'ly not more than eating any other protein -- the chlorophyll molecule will have to be digested before it can be absorbed by the body. However, foods that contain lots of iron DO help make more hemoglobin, because iron is an essential part of it. 24.23.196.85 (talk) 00:00, 21 September 2013 (UTC)

The heme molecule is not a protein, it's a hydrocarbon porphyrin ring surrounding an associated iron ion then associetd with a protein globin molecule. Chlorophyll has a porphyrin chlorin ring surrounding a magnesium ion and attached to a phytol tail. Our articles discuss the breakdown of used heme molecules by the liver and their creation in the same system that deals with cholesterol and steroids. See porphyrin for its synthesis. A search for articles on chlorophyll digestion does not make it likely that chlorophyll is reused for hemoglobin synthesis. μηδείς (talk) 00:39, 21 September 2013 (UTC)

I don't see much since [7] which says:

"After release from the plant food matrix, natural chlorophyll (CHL) derivatives are exposed to the acidity of the gastric digestion resulting in conversion to respective metal-free pheophytins (PHE). Within the upper small intestine, PHE derivatives partition into bile salt lipid micelles resulting in solubilization of PHE and movement across the unstirred water layer and ultimately into the enterocyte presumably by passive diffusion [49]. The extent to which natural chlorophyll derivatives are metabolized and/or secreted into circulation is currently unknown. Chlorophyllin: After digestive release of water-soluble SCC derivatives, significant degradation of Cu-chlorin e6 derivatives occurs, leaving primarily Cu-chlorin e4 and potentially residual amounts of Cu-chlorin e4 ethyl ester [50]. Uptake of SCC derivatives by intestinal cells seems to proceed predominantly by a facilitated process, with absorbed SCC derivatives efficiently effluxed back to the luminal compartment [50] by unidentified efflux system (potentially BCRP/ABCG2 55, 56 and 57). A portion of the internalized SCC derivatives is passed from the enterocyte into circulation as noted by Egner et al [38]. The extent to which SCC derivatives are metabolized and the extent to which the metabolites may be transported out of the enterocyte are currently unknown."

I should point out, however, that despite the superficial similarity you can notice a number of little variations around the edges between the heme and chlorophyll. As a rule, removing or changing this sort of carbon-carbon bond at the edge of an aromatic ring complex is not easy to do - my gut feeling is that biology is going to deal with that sort of problem either by doing nothing to the structure and excreting the remnants at some point, or else by adding lots of oxygen, completely opening up the rings and splitting it to small compounds, when then would be part of general metabolism. Wnt (talk) 14:33, 22 September 2013 (UTC)

That's your gut feeling about digestion? DMacks (talk) 07:39, 23 September 2013 (UTC)