Wikipedia:Reference desk/Archives/Science/2017 February 18

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February 18

What is the difference between IS:733 and IS:736

Dear all, Kindly clarify what is the difference between aluminum alloy standards as mentioned in Indian standards Is:733 and Is:736. for example i am giving manufacturing drawing for a milled box sizing 60x60x40 mm. Should i mention material to be as per IS:733 or IS:736. Ex: 1.Material:Aluminium alloy To IS:(733 or 736),Grade:64430-T6 Please clarify SD — Preceding unsigned comment added by Sameerdubey.sbp (talk • contribs) 03:55, 18 February 2017 (UTC)

Please note: Someone here might be able to tell you something about the difference between the standards, but you should understand that we cannot tell you what you "should" do. We're not here to give advice, only information, and legal advice is something we have specifically decided we're not competent to give. We are very unlikely to have someone around with real competence regarding technical points of Indian law, and even if someone here says they do, we have no way to verify he is telling the truth. Wnt (talk) 10:04, 18 February 2017 (UTC)

One is for aluminium bars, rods and sections - the other is for aluminium plate. Use the one relating to the type of aluminium that will be used to manufacture whatever you are designing. If you start with aluminium sections (which would seem probable if your box is milled), it will be 733 - if you start with aluminium plate, it will be 736. Wymspen (talk) 12:29, 18 February 2017 (UTC)

Thanks wymspen SD — Preceding unsigned comment added by Sameerdubey.sbp (talk • contribs) 04:25, 7 March 2017 (UTC)

Scientific coincidence

The Titius–Bode law is an example of a scientific coincidence. Are there other examples of scientific coincidence apart from it? --IEditEncyclopedia (talk) 15:09, 18 February 2017 (UTC)

I am a little confused. What is the difference between "scientific coincidence" and "coincidence"? DrChrissy ^(talk) 16:05, 18 February 2017 (UTC)

The OP may be looking for other examples of apparent scientific laws that have turned out to be rules that don't really apply. An example is Vitalism, the notion that living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things. It was discredited by Friedrich Wöhler's discovery in 1828 that Urea can be produced from inorganic starting materials. See the article about Superseded scientific theories for other examples. Blooteuth (talk) 17:09, 18 February 2017 (UTC)

Dirac large numbers hypothesis may be of interest. Loraof (talk) 17:38, 18 February 2017 (UTC)

A famous example is that a total solar eclipse is just possible. Solar eclipse#Types says: "The Sun's distance from Earth is about 400 times the Moon's distance, and the Sun's diameter is about 400 times the Moon's diameter. Because these ratios are approximately the same, the Sun and the Moon as seen from Earth appear to be approximately the same size". It has been called a sign that God designed it. If you believe more in science and an old universe then the Moon is moving slowly away from Earth so the coincidence is the current distance. PrimeHunter (talk) 18:05, 18 February 2017 (UTC)

Did you know total solar eclipses would be impossible if the orbits were perfect? An averagely far Sun is 0.533° wide and the closest you can get to an averagely far Moon makes it 0.527° wide (both sea level and in an aircraft). The only thing making total solar eclipses possible at low Earth orbit or below is that the Moon is sometimes closer than average (less often, the Sun being further than average is sufficient) Sagittarian Milky Way (talk) 19:51, 18 February 2017 (UTC)

See also Mathematical coincidence#Fine-structure constant. The article mentions other examples from the physical world but they rely on units invented by humans. PrimeHunter (talk) 18:13, 18 February 2017 (UTC)

Can dogs and cats eat cooked foods?

What happens if they are fed cooked foods? Are they really carnivores? Why do packaged pet foods contain fruits and vegetables? Can they be fed peas and carrots? 166.216.159.13 (talk) 15:40, 18 February 2017 (UTC)

Regarding dogs. Please read our article Dog food. Dogs are usually classified as carnivores but contrary to popular use of the term, as the article Carnivore explains, this does not mean they eat only meat, rather, carnivores get their requirements from a diet consisting mainly or exclusively of animal tissue. Dog food also explains dogs can eat cooked meat - most tinned dog food is cooked. They can also be fed a vegetarian diet. DrChrissy ^(talk) 15:59, 18 February 2017 (UTC)

Regarding my Cat. 1) Eats it, asks for more and never says thank you. 2) He's a facultative carnivore not an obligate carnivore, but why bother hunting prey when master serves Cat food (see article) that may indeed contain some plant matter, just as long as no one seriously expects to convert this cat to Vegetarianism? Blooteuth (talk) 16:52, 18 February 2017 (UTC)

Why are you stating the cat is a facultative carnivore when there is a multitude of scientific papers stating they are obligate carnivores, e.g. [1]? DrChrissy ^(talk) 17:03, 18 February 2017 (UTC)

Yes, CATS ARE OBLIGATE CARNIVORES. IT IS COMPLETELY INCORRECT TO SAY THEY ARE FACULTATIVE CARNIVORES, AS SHOWN BY NUMEROUS RELIABLE SOURCES LINKED ABOVE AND BELOW. Please forgive my typographic emphasis - this is important, and an issue of animal welfare, so I wanted to make it unmistakably clear for any casual reader :) SemanticMantis (talk) 23:26, 18 February 2017 (UTC)

This vegan cat food site admits "Some cats have a more difficult time adapting to a vegan diet than others". Note that domestic cats know only what they like and not what is good for them, which is why they are liable to ingest things that do them no good, such as Melamine in wheat glutin (see 2007 pet food recalls) and lactose in cow's milk that gives pussy Diarrhea. See also. Blooteuth (talk) 17:29, 18 February 2017 (UTC

I really don't think it is appropriate on a sci-ref desk to try and counter my RS with information from web-site advertisements. Please could you provide an RS that states cats are facultative carnivores. DrChrissy ^(talk) 18:10, 18 February 2017 (UTC)

Cats are natural carnivores which occasionally eat some vegetable matter such as grass. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:26, 18 February 2017 (UTC)

Dogs also eat plant matter but they are classified as carnivores. Cats are classified as "obligate carnivores" for a scientific reason. If we are going to bend or misuse these scientific terms on this REFERENCE desk, the least we owe our readers are RS to support the terminology we use when this clashes with other RS. RS please. DrChrissy ^(talk) 18:31, 18 February 2017 (UTC)

Both cats and dogs are members of the order carnivora, but that is an evolutionary classification that does not necessarily have anything to do with current culinary requirements or preferences. Cats are obligate carnivores because they rely on external sources of arginine and taurine. Arginine is primarily sourced from meat, and AFAIK there is no significant natural vegan source of taurine. If a cat's nutritional needs are met, they can, of, course, eat some additional plant food. Most of that is not poisonous to cats, it just does not meet their requirements. Dogs, on the other hand, can live on a mostly vegetarian diet - indeed, some of the key genetic differences between wolves and dogs relate to the efficient digestion of starchy foods in dogs. --Stephan Schulz (talk) 19:07, 18 February 2017 (UTC)

Our article on taurine says that about 3,000 tons of it are synthesized annually for addition to pet foods. I may not be a fan of veganism but I can't say no to a good chemistry experiment on animals. ;) Wnt (talk) 19:40, 18 February 2017 (UTC)

Point taken and qualifier inserted above. --Stephan Schulz (talk) 19:44, 18 February 2017 (UTC)

I feel it is required to point out that cats are obligate carnivores, as any reliable source will tell you. This means forcing them into a vegan or even vegetarian diet is highly unnatural at best, and really can only be described as animal cruelty. It will lead to deficiencies in taurine (causing retinal degeneration and cardiomyopathy), arginine (causing dangerously high blood ammonia levels), arachidonic acid and other essential fatty acids (causing problems with liver, kidney, skin and more), and other essential nutrients such as iron, calcium and phosphorus. Lack of meat also screws with cats' urine pH, possible causing kidney stones, and the high carbohydrate nature of vegetarian/vegan foods puts them at risk of diabetes. Vegan diets would need extensive supplementation to be even remotely healthy for a cat. The link provides by User:Blooteuth is incorrecnt. The company is either lying for the economic benefit of their company, or incredibly ignorant. Dogs are of course essentially omnivores, and are much more flexible when it comes to diets. Fgf10 (talk) 20:52, 18 February 2017 (UTC)

This reference is a very accesible analysis of why dogs are classified as "carnivores" and cats as "obligate carnivores"-VERONIQUE LEGRAND-DEFRETI. Proceedings of the Nutrition Society (1994), 53, 15-24. Differences between cats and dogs: a nutritional view. DrChrissy ^(talk) 20:57, 18 February 2017 (UTC)

Excellent link, should have looked for something like that, rather than type out that whole rant. Much obliged for the reference. Fgf10 (talk) 21:06, 18 February 2017 (UTC)

Absolutely no problem at all - that is what this ref-desk is for. Your post was not a rant - it was a clearly informed contribution to the discussion which is always welcome. DrChrissy ^(talk) 23:45, 18 February 2017 (UTC)

You can feed your pets some vegetables as snacks, but there are some you should never feed them. The ASPCA has a decent list here: link EvergreenFir (talk) 17:09, 18 February 2017 (UTC)

sentiment

Cats are obligate carnivores, but vegetable products are added to cat food to provide fiber and nutrients that they would get in the wild from animal sources. For example, they get fiber from hair and feathers, but that is replaced with plant fiber in cat food. They also require a lot of fat in their diets, and can be harmed by garlic, onions, and other ingredients commonly added to human food. Also, they do not require vitamin C in their food, as their body manufactures it and unlike humans, they need complete proteins in their diets as they cannot manufacture them from amino acids. That's why you should not feed cats table scraps. Dogs are much closer to humans in their diets, which is why dog food is different from cat food. TFD (talk) 20:38, 18 February 2017 (UTC)

Distraction ---Sluzzelin talk 18:54, 19 February 2017 (UTC)

(offending post was here) Asmrulz (talk) 04:15, 19 February 2017 (UTC) This post is absolutely no help whatsoever to this thread and I ask an uninvolved editor to strike it or perhaps place it in a collapsible box. DrChrissy (talk) 23:57, 18 February 2017 (UTC) You should discuss this on the user's talk page rather than screwing around with his edit here. ←Baseball Bugs What's up, Doc? carrots→ 01:12, 19 February 2017 (UTC) Thanks. I had already removed it (for OP's sake) but the user reinstated it for some reason, with their silly formatting, too Asmrulz (talk) 04:15, 19 February 2017 (UTC) ...and I stand by the general sentiment in it Asmrulz (talk) 04:22, 19 February 2017 (UTC) For those who might not be aware of markup for deleted text, please see [2]. By simply deleting the comment, the ensuing thread can become confused. Hardly "screwing around". DrChrissy (talk) 12:58, 19 February 2017 (UTC) Personally, given that it was in small text, I'd consider the "offending post" acceptable (small text being used to imply less-than-scholarly remarks), but let's not go off in tangents, or all this argument should be hatted. Eliyohub (talk) 18:08, 19 February 2017 (UTC) If it had been slightly related to the question, I would have let it go. However, it seemed to me to be more a statement of how the OP should run their lives. Totally unacceptable for a SCI-REFERENCE desk. DrChrissy (talk) 19:05, 19 February 2017 (UTC)

To address some of the other Q's:

1) There's nothing in being a carnivore which requires eating raw food.

2) As for adding fruits and vegetables, they may provide needed dietary fiber. In nature, eating a mouse would likely include it's (vegetarian) intestinal contents, so a bit won't hurt. Also, such a pet food may sell better, if people think it's better for their pet, regardless of if it really is. In the past, they've included things like sawdust for fiber, sometimes disguised as "cellulose", but that just sounds bad and turns off potential buyers. StuRat (talk) 23:55, 18 February 2017 (UTC)

Scientific American "Veggie Cat Food? Why Not All Cats Need Meat" The vegetarian pet debate is a contentious one among vegetarian pet owners and veterinarians and is one not likely to go away anytime soon.

Web MD says If you are considering a vegan or vegetarian diet for your dog or cat....Only consider or feed commercial diets that have gone through feeding trials and meets the requirements for AAFCO (Association of American Feed Control Officials) compliance.

In some medical cases (allergies, liver or bladder disease) veterinarians use specially formulated pet foods only available by prescription that are made from nonmeat protein sources (egg or soy, for example). Blooteuth (talk) 00:11, 19 February 2017 (UTC)

There could also be moral or religious reasons. After all, a Jain isn't allowed to cause the death of one animal to feed another, right? StuRat (talk) 03:48, 19 February 2017 (UTC)

Are they allowed to deliberately help the cat nab mice, or give the cat a live mouse to kill and eat? Eliyohub (talk) 18:09, 19 February 2017 (UTC)

No, not if I read our article correctly: "The first major vow taken by Jains is to love and cause no harm to other living beings. It involves minimizing intentional and unintentional harm to other living creatures by actions, speech or thoughts. The vow of ahiṃsā is considered the foremost among the 'five vows of Jainism'.".StuRat (talk) 18:59, 19 February 2017 (UTC)

A proper follower of Jainism wouldn't have a pet cat in the first place, so an argument about feeding the cat wouldn't come up. 209.149.113.5 (talk) 13:47, 21 February 2017 (UTC)

If they found a starving cat, their principles would seem to require them to help it, but without harming any other animals. Hence the need for vegetarian cat food. I imagine milk would be OK, although that wouldn't make for a complete diet for an adult cat. StuRat (talk) 19:44, 21 February 2017 (UTC)

I didn't see a link for that article about dog-cat differences, so here it is: [3] notably it cites

1. "the cat has limited ability to regulate the catabolic enzymes of amino acid metabolism, which causes the cat to require a higher level of dietary protein for maintenance than the dog
2. the cat has a lower capacity to synthesize the sulphonic acid taurine than the dog and is unable to conjugate bile acids to glycine. Thus the cat, unlike the dog, cannot meet its taurine requirement from dietary S-containing amino acids
3. the cat cannot synthesize sufficient nicotinic acid from tryptophan because of an increased activity of alpha-picolinic acid decarboxylase (EC 4.1.1.45) leading to the endproduct glutamate rather than nicotinic acid
4. the cat is unable to convert carotene to retinol and, therefore, cannot satisfy its vitamin A requirements with a herbivorous diet alone
5. the cat cannot convert sufficient linoleic acid to meet its requirement for arachidonic acid
6. the cat seems to be unable to cope with high levels of carbohydrate in its diet and appears to be in a constant state of gluconeogenesis."

Wnt (talk) 22:00, 19 February 2017 (UTC)

Antidepressant vs recreational drugs

In as much as I understand it, most, but not all, antidepressants focus on serotonin—I do not profess to know the mechanism. However, recreational drugs seem in most, but not all, cases to focus on dopamine. Why the discrepancy?--Leon (talk) 18:28, 18 February 2017 (UTC)

They're different neurotransmitters that do different things. See Neurotransmitter#Examples_of_important_neurotransmitter_actions for a cursory overview. Shock Brigade Harvester Boris (talk) 19:24, 18 February 2017 (UTC)

Yes, but both antidepressants and recreational drugs are used for, in very broad terms, to help people "feel better", or at least "less bad". So one might expect them to work with the same neurotransmitters in more cases than not.--Leon (talk) 19:36, 18 February 2017 (UTC)

It depends on what neurotransmitter you want to mess with. Some depressed patients in a clinical setting respond positively to Dopamine reuptake inhibitors others need Norepinephrine–dopamine reuptake inhibitors. Some street drugs mess with your serotonin levels and druggies choose, MDMA, aSerotonin releasing agent.

I believe that in many cases where your split (in antidepressant/serotonin and recreational drug/dopamine) is wrong. — Preceding unsigned comment added by Hofhof (talk • contribs) 20:03, 18 February 2017 (UTC)

So, if someone needs serotonin but not dopamine, does that suggest, albeit weakly, that they may not enjoy e.g. heroin?--Leon (talk) 20:18, 18 February 2017 (UTC)

If someone is low on serotonin to a pathological level, he will enjoy heroin and can get easily addicted to it. Heroin messes with a lot of neurotransmitters, including serotonin. Source: [4]. Also remember that depressed people can have panic attacks or not be depressed all the time. Heroin will be pretty enjoyable for them. Hofhof (talk) 20:33, 18 February 2017 (UTC)

The dirty truth that us neuroscientists don't like to say very often is that we really don't know anything about depression. The use of serotonin modulating drugs comes from observations of low levels of breakdown products of serotonin in the cerebrospinal fluid some (not all) depressive patients, and the clinical improvement some (again, not all) patients see when prescribed serotonin modulating drugs. However, we don't know why serotonin is down in some patients, we don't know how serotonin alters mood, and we don't know why some patients don't respond to serotonin modulating drugs. Of course, the pharmaceutical industry has made good money on selling their SSRIs, so will glance over these minor details. Why we don't know more is a long and ugly story, but it has a lot to do with our inability to really model depression in animals models. What we do know is that for some patients, cognitive therapy, exercise , or other drugs such as mentioned above, work a lot better than SSRIs. Hell, in some trials even placebos work as well.

As for dopamine and recreational drugs, dopamine is crucial for the reward system in the brain. It is thus involved in 'pleasure' and positive reinforcement. Fgf10 (talk) 21:04, 18 February 2017 (UTC)

Interesting on all counts...

Perhaps a slight digression: I've read conflicting accounts on the possibility of not enjoying opioids. Some people believe it is almost impossible because "everyone" likes dopamine, but some people seem to dislike opioids. How is it possible if dopamine feels good?--Leon (talk) 21:11, 18 February 2017 (UTC)

Also Fgf10, whilst you are explicit on some points, it is not at all clear on what you or the establishment has to say about the role of serotonin. Is it necessary for the feeling of pleasure, or not?--Leon (talk) 21:34, 18 February 2017 (UTC)

The first problem with answering that question is to define 'pleasure'. Human affection is a mess of complex processes, which are poorly defined, and the neural basis for even a single of those processes is generally poorly defined. We know a lot of effects of serotonin, see for instance serotonin syndrome. You'll note everything mentioned in that article is a physical property, such as body temperature and pupil diameter, which are easily measured. How do you measure pleasure? In humans, this is normally done with questionnaires, which are a poor measure of anything. To directly measure the effects of serotonin on pleasure (whatever your definition), you'd have to drastically alter the levels and measure the effects. This is essentially impossible in healthy humans (for practical and ethical reasons). Therefore we usually do these experiments in animals and try to extrapolate the results. However, if measuring 'pleasure' in humans is difficult, try doing it in animals. We're stuck with poor proxy measures such as (an)hedonia, measured by preference for sweet foods etc. Long story short, we don't really know how serotonin affects mood. That is does seems true, as raising serotonin levels in depressive patients often elevates mood. Your question perfectly illustrates how seemingly simple questions are still really difficult to asnwer. Good things they are, or I'd be out of a job! Fgf10 (talk) 23:08, 18 February 2017 (UTC)

Our article on the Nucleus accumbens - the reward and pleasure center of the human brain - may be helpful to your understanding. Opiates, drugs that regulate reuptake of serotonin and other neurotransmitters, and even sugar stimulate different parts of the nucleus accumbens in different ways. Instead of reproducing that article in large part, I'll just point out two relevant sections of the article: Nucleus_accumbens#Neurotransmitters and Nucleus_accumbens#Function and let you discover the fine points of how recreational drugs tickle the nucleus accumbens (reinforcing both recreational use and addiction to drugs) as opposed to how drugs that make more serotonin and other neurotransmitters available to circulate in the brain do that.

As Fgf10 says, we're not really sure how selective serotonin reuptake inhibitors work in treating depression, but our article on the nucleus accumbens Nucleus_accumbens#Depression points to research showing some success in treating depression by electrically stimulating the nucleus accumbens with deep-implanted electrodes. The authors of that paper point to two other research papers they say demonstrate that parts of the nucleus accumbens don't work well in depressed patients, and that some dopaminergic compounds such as dextroamphetamine (used as "dopaminergic probes") show a detectable change in the cellular metabolism of parts of the nucleus accumbens. loupgarous (talk) 02:07, 19 February 2017 (UTC)

About serotonin versus dopamine, it's not at all a case of a clear divide. Almost all antidepressant medications have at least some effect on both transmitters. The SSRIs (SS=selective serotonin) have relatively little dopaminergic effect, but it is not zero. And people who have depression vary greatly as to which antidepressant works for them. Also, one should not understand the effects of drugs that affect reuptake as simply "increasing" or "decreasing" the amount of neurotransmitter. (Inhibit reuptake, and there is more transmitter in the synapse but less available to be released from the neuron that releases it.) Perhaps it has something to do with how the timing of availability of the transmitter affects neuron firing, but neuroscientists do not have any clear understanding of that yet. And as for recreational drugs, cocaine almost entirely affects dopamine whereas LSD almost entirely affects serotonin. And LSD obviously is nothing like an SSRI antidepressant. Again, recreational drugs differ greatly as to which transmitters they affect the most. And about enjoying or not enjoying opiates, it's very interesting that during the Vietnam War, many US military people used heroin – at the end of the war, most just walked away from heroin with no addiction, but a subset of the population were addicted for life. Very likely, there are genetic differences that cause that, but their nature is presently unknown. --Tryptofish (talk) 00:50, 20 February 2017 (UTC)

Killing a tree without chopping it down

Would drilling a hole into a tree and pouring weed killer into the hole kill it? — Preceding unsigned comment added by 189.201.241.54 (talk) 19:22, 18 February 2017 (UTC)

Check out girdling. EvergreenFir (talk) 19:27, 18 February 2017 (UTC)

You would probably need to drill several holes at various points around the circumference to have the same effect as girdling. Both glyphosate and hormone weedkillers such as 2,4-Dichlorophenoxyacetic acid can be used to kill trees in this way. Another method is a circle of copper nails. Dbfirs 20:54, 18 February 2017 (UTC)

• See Auburn_Tigers#Toomer.27s_Trees_poisoned. μηδείς (talk) 23:55, 22 February 2017 (UTC)

Stage of development when freezing developing humans

Up to what stage (and why not further) can you freeze a developing human? I assume that's past being a zygote, but before turning into a baby. Where and how can you determine the limit?--Hofhof (talk) 20:10, 18 February 2017 (UTC)

This is just a guess but I would imagine it is the point just before when cells need chemical signals to instruct them to start specializing into liver cells, brain cells, arms and legs etc., (thalidomide interferes with the chemical instructions needed for newly forming cells).--Aspro (talk) 21:40, 18 February 2017 (UTC)

Embryo cryopreservation may be a good starting point. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:40, 18 February 2017 (UTC)

Illnesses from indirect accidental consumption of animal faeces during outdoor activities

Are there a lot of known cases of people who do outdoor activities in first world countries becoming ill from indirect consumption of animal faeces? For example they touch something with traces of animal faeces (maybe touching equipment which has touched it) and consume food with their hands. 2A02:C7D:B957:3B00:74AC:C58F:30BC:44E2 (talk) 23:52, 18 February 2017 (UTC)

Define "a lot". Foodborne illness often results from consuming something contaminated with fecal matter, though I'm not sure this has any particular correlation with "outdoor activities". There are reasons other than fecal contamination to wash your hands; your hands can carry other pathogens such as influenza and bacteria that can infect wounds (like ones you might get from outdoor activities). --47.138.163.230 (talk) 00:29, 19 February 2017 (UTC)

Some children have lost their sight through touching dung and then rubbing their eyes. 80.5.88.48 (talk) 08:37, 19 February 2017 (UTC)

Toxoplasmosis can definitely come from handling the faeces of an infected cat. I'm sure others can quote similar animal-faeces-borne infections? Cats are usually fastidiously clean animals, though, and tend to cover their faeces with either soil or kitty litter. But they do tell you to be careful. Eliyohub (talk) 17:58, 19 February 2017 (UTC)

Hantaviruses, normally found in rodents, can be transmitted to humans through feces and are found throughout Europe and North America. -165.234.252.11 (talk) 20:48, 21 February 2017 (UTC)