Wikipedia:Reference desk/Archives/Science/2017 August 13

= August 13 =

Nicotine addiction
I'm curious what nicotine addiction feels like so I plan on doing e-cigarette's. I'm fine with the crash I'll experience for a few weeks after quitting but I'm wondering if it'll be like low-level craving it for years/rest of my life? I don't want to wake up everyday forever thinking damn I wish I had some nicotine. 2.102.184.47 (talk) 03:44, 13 August 2017 (UTC)


 * Please read the instructions at the top of the page, we cannot make medical predictions or speculate on the future. μηδείς (talk) 04:05, 13 August 2017 (UTC)


 * I think dismissing this is an unjustifiable cop-out. Nicotine is not a prescribed medication, and sources on the rapid onset of addiction are available:     Note these sources all agree that one can become addicted within two days, though it may not happen that fast.  As in Charlottesville, there is more harm to be done by suppressing discussion than by permitting it. Wnt (talk) 12:05, 13 August 2017 (UTC)


 * The FDA has regulated all nicotine products since August 2016 https://www.fda.gov/tobaccoproducts/labeling/rulesregulationsguidance/ucm394909.htm. This is a request for personal advice on how the use of a drug will affect the individual, a classic no-no. μηδείς (talk) 15:24, 13 August 2017 (UTC)


 * I tried smoking as a youth, but it just made my heart pound, so I could not achieve the habit. Alcohol and caffeine worked better. It might be genetics. Edison (talk) 02:44, 14 August 2017 (UTC)

identify an insect
Triangular shaped bug about 5-7 millimetres long. I think it is initially translucent, then green and finally brown (not sure though). Dozens of this insect are present on the stalks of a bean plant. It is not feeding on the leaves, but probably on the stalk. Not found on nearby plants until the bean stack was cut down / pruned. Ants seem to interacting with it a lot (I think). Google reverse image search wasn't helpful. — Preceding unsigned comment added by Cplusplusboy (talk • contribs) 07:04, 13 August 2017 (UTC)


 * These look like larvae of some species of Cicadellidae or leafhoppers, sap sucking insects that probably produce honeydew which accounts for the opportunistic (or farming) ants. There are very many species and some specialist sources will probably be required to establish the exact indentification. Compare with this image http://www.ozanimals.com/Insect/Leafhopper-larvae/Cicadllidae%20family/spp2.html. Richard Avery (talk) 10:18, 13 August 2017 (UTC)


 * The thorn shape reminds me of a treehopper - for example, reviews that this shape is pretty representative, and involves a much modified pronotum... the setae do make it seem more like a nymph, though early treehopper stages apparently don't have the thorn shape.  this photo of Acanthuchus trispinifer looks similar but not identical to me.  Our resources, including Wikispecies, seem almost entirely deficient on any kind of Terentiini other than this species. Wnt (talk) 11:56, 13 August 2017 (UTC)


 * The pictures in the landcareresearch.co.nz link are the ones (unless this shape and colour are commonly found in other species). The green photos with the pyramid shaped head and curved tail I posted are nymphs and the brown ones not posted here is the adult tri-horned treehopper as per the website. Thanks Cplusplusboy (talk) 16:37, 13 August 2017 (UTC)


 * Do the ants actively protect these from predators? I want to know whether I can get these pests to get eaten by predators if I get rid of the ants. The ants seem to have made a colony under the soil very close to the plant on which these insects were found Cplusplusboy (talk) 16:46, 13 August 2017 (UTC)
 * Ants do protect their honeydew herd, also it can be discuss if it some kind of "active" behavior, or just the result of their natural aggressiveness against pretty everything except this herd. Gem fr (talk) 08:05, 17 August 2017 (UTC)

Pressure during gravitational collapse
How much pressure approximately (say, in GPa) is generated by gravitational compression during gravitational collapse of a star (also in cases of black holes)? Thanks.--212.180.235.46 (talk) 14:46, 13 August 2017 (UTC)
 * I don't know, but add it to Orders of magnitude (pressure) when you find out. Abductive  (reasoning) 19:50, 13 August 2017 (UTC)


 * If I haven't lost a decimal place, I believe the sun's core is roughly 34 million GPa, which should give a representative idea of the pressures involved. Dragons flight (talk) 10:44, 14 August 2017 (UTC)


 * Well, according to our neutron star article the pressure near the center of a typical one is on the order of 10^35 Pa, or 10^26 GPa, which is, um, a bit higher than your figure. (This already appears in the "orders of magnitude" list.) Looie496 (talk) 19:45, 14 August 2017 (UTC)

Fat
What is the maximum dietary fat intake per day and over what time period to cause rabbit starvation? Does the type of fat make any difference (animal vs plant)? The article is vague on the specifics. Thanks — Preceding unsigned comment added by 134.213.208.187 (talk) 18:56, 13 August 2017 (UTC)


 * Rabbit starvation occurs when there is excessive protein and too little fat in the body. This study suggests that there is no difference between lentil-based protein and animal-based protein on nitrogen absorption and thus hints that the lentil-based protein can be used to feed moderately malnourished children. Dr. Michael Greger reports that eating a high-fat, high-protein animal-based diet faces a much higher mortality rate than eating a high-fat, high-protein vegetable-based diet here and the Standard American Diet. SSS (talk) 19:35, 13 August 2017 (UTC)


 * Looking at Vegetarian nutrition, I see no problems with plant-based fats (...Yummmm. Avocados...). Vegitarians and vegans have to take some extra care to avoid nutrient deficiencies, but millions and millions of people do it and live healthy lives without eating animals. Note: I am not a vegetarian; I am just reporting what the science says. --Guy Macon (talk) 21:36, 13 August 2017 (UTC)
 * Presently the US government suggests that a person who needs 2000 kcal per day consume no more than 65 grams of fat a day and of those that no more than 20 grams be saturated fat. If the total energy need is 2500 kcal then the corresponding numbers are 80 g fat and 25 g saturated fat. See also . The nanny state worries about us consuming saturated fat, sugar, and caffeine.Edison (talk) 02:40, 14 August 2017 (UTC)


 * Here is a current headline about a woman who died from a high-protein diet. μηδείς (talk) 21:34, 15 August 2017 (UTC)

Tunnel, sea
Are tunnels crossing the sea, like the euro tunnel, a tube over the sea bed or are they dig under the ground like a subway? — Preceding unsigned comment added by 31.4.149.201 (talk) 22:22, 13 August 2017 (UTC)
 * The Channel Tunnel was dug through the sea bed.. You can see a cross-sectional diagram at that article. Rojomoke (talk) 23:28, 13 August 2017 (UTC)


 * I think in general, laying a tube over the sea bed but deep under water has the problematic aspect that a rupture would make immense quantities of water enter at once. A tube beneath the sea bed can be dug like any tunnel beneath the water table (including tunnels on "land") - to be sure, it is immersed, but the permeability of the rock determines how rapidly water can enter. Wnt (talk) 23:44, 13 August 2017 (UTC)

Both techniques are possible. As noted, the Channel Tunnel (or Eurotunnel) was bored below the seabed, but on the other hand, the Transbay Tube is indeed "a tube over the sea bed". However, note that while both are under arms of the sea, the English Channel is a good deal deeper than San Francisco Bay.

By the way, note that subways are not always "dug under the ground". Another common technique is to dug them into the ground as open trenches which are then then covered over. See Tunnel. --69.159.60.147 (talk) 06:19, 14 August 2017 (UTC)


 * I've often wondered, if the Transbay Tube were ruptured, how many stations in the City would be flooded! —Tamfang (talk) 05:34, 16 August 2017 (UTC)


 * That article links to Undersea tunnel but it doesn't really discuss construction methods that much. However it does link to our article on the Immersed tube tunnel. From there, you'll find a link to the article on the theoretical Submerged floating tunnel. Nil Einne (talk) 07:20, 14 August 2017 (UTC)
 * BTW those articles claim without sources that Marmaray is the deepest immersed tube tunnel in the world, and per our article its deepest point is around 60m. Busan–Geoje Fixed Link is said to be the deepest road immersed tube tunnel and our article suggests it could be the second deepest, being 48m at its deepest point. By comparison, our article says the Channel Tunnel is 115m below the sea level at its deepest point although it's also 75m below the sea bed. Going back to the earlier articles, we find Eiksund Tunnel which is said to be the deepest overall and is 287m at its deepest point. However it seems Rogfast is probably going to be 390m at its deepest point. Nil Einne (talk) 07:32, 14 August 2017 (UTC)


 * Øresund Bridge is another to look at. 3.5km of buried tube tunnel. Andy Dingley (talk) 09:29, 14 August 2017 (UTC)


 * Wikipedia has an article titled Tunnel construction which may be a good place to start your research. -- Jayron 32 11:01, 15 August 2017 (UTC)

I believe that the Washington DC Subway system has used both. I believe the Tunnel on the Blue/Orange/Silver line under the Potomac was dug under the ground, the one on the Green Line under the Anacostia is in a tube sitting on the bottom.Naraht (talk) 19:43, 15 August 2017 (UTC)

DIY crappy chokes for VGA cables?
The VGA cables I have don't have chokes on and I think there is some interference between them or them and something else. Is there something I can use to make a choke that I can apply to the cable? I have a few ferrite toroids but I can't get them around the cable without cutting the cable first (not doing that, obviously). I have some strips of thin steel I could wrap around and maybe magnetise first if that would make a difference. --145.255.246.8 (talk) 23:26, 13 August 2017 (UTC)
 * A ferrite choke, scored with a file, snappped in half and then superglued back together is still a reasonably efficient choke.  There are also ferrite rings made in two pieces, ground smooth on the mating surfaces, and held in a snap-lock plastic housing. You can often find these on old cables: monitor or keyboard. I habitually recycle these when scrapping old keyboards, they're often useful for ad hoc suppression tasks. Andy Dingley (talk) 09:26, 14 August 2017 (UTC)


 * https://www.amazon.com/dp/B01MRIKIJX/ref=asc_df_B01MRIKIJX5121726 Also see: http://palomar-engineers.com/ferrite-products/snap-on-split-beads --Guy Macon (talk) 09:31, 14 August 2017 (UTC)

Industrial uses of seawater
Here in the non-coastal US, we always have enough water for drinking and other non-agricultural uses (the only significant effect of droughts is that farmers who can't irrigate may lose their crops), and when non-potable water is needed for ordinary industrial purposes (firefighting, power-washing, dust suppression, etc.), we routinely use water from the mains or from a river if it's available. Can seawater generally be used for similar purposes? Geography of Singapore notes that their freshwater needs surpass what they get from rainfall, and I'm left wondering if they're able to use seawater in such contexts (i.e. if they couldn't, they'd have to import far more water than they do now), or if for some reason it's impossible and they have to import water for industrial purposes as well. Nyttend (talk) 23:47, 13 August 2017 (UTC)

PS, I'm familiar with fireboats; I'm wondering if it's practical to set up water mains for seawater for the sake of firefighting that's not near the shoreline. Given Singapore's numerous high-rises, I doubt they'd want to rely on tanker engines, and obviously they can't use long fire-hoses to pump water for non-shoreline fires. Nyttend (talk) 23:50, 13 August 2017 (UTC)


 * Bad idea, contaminating all the waste water with salt (if you recycle waste water for drinking etc). Also, what proportion of the ciy's water usage is fire fighting - not much i'd guess rather negating my first point. Greglocock (talk) 01:57, 14 August 2017 (UTC)


 * It suggested to use seawater for cooling in Singapore [//www.pub.gov.sg/research/industrialwatersolutions]. I suspect it happens in practice but am lazy to search for sure but it definitely happens elsewhere although this does require careful consideration of the cooling system design, and also leads to concerns over the local marine environmental effects of tie discharge   . A particularly common user is power plants but again there's a lot of controversy over the effects of such practices on the local marine enviroment, especially with once through systems    . Nil Einne (talk) 07:14, 14 August 2017 (UTC)
 * discusses using sea water in mining operations but although it does mention the possibility of using it straight, all the examples cited seem to involve some desalination. Nil Einne (talk) 07:35, 14 August 2017 (UTC)
 * When I lived in Hawaii, the university installed seawater cooling for multiple buildings. It isn't really use of seawater. They take a coolant (not seawater) and pump it down deep into the ocean. The coolant gets cold. It is pumped back up and circulated through the walls of a building. It cools down the building. It is then pumped back down into the ocean. I would call it deep-ocean cooling, not seawater cooling. 209.149.113.5 (talk) 14:56, 14 August 2017 (UTC)
 * For clarity are you referring only to the system you encountered or are you claiming this applies to all systems? If the later, I suggest you read the links carefully as some of them explicitly talk about using sea water for the purpose, including the problems of designing the piping as well as other structures, as well as pumping it around building for heating to reduce the environmental impact of warm seawater discharge. Another issue is the addition of materials like chlorine to reduce biofouling and the impact of this when the sea water is discharged. Likewise while technically the system you described is similar to a once through cooling system I guess, AFAICT, the term only applies to systems where the sea water is taken in and directly discharged after use. I did come across some sources which seemed to refer to directly using the ocean for cooling, but intentionally didn't link to them. I did just notice we have an article Deep water source cooling which seems to mostly discuss systems which directly use sea water although it isn't always clear.  I also just came across this system in Honolulu which is a little different from the one at the university you mentioned . If I understand the diagram and description correctly, it doesn't use the seawater for cooling buildings, but also doesn't directly cool in the ocean. Instead seawater is taken to a cooling station and there used to cool freshwater. The seawater is returned to the ocean and the freshwater used to cool buildings. So sort of an intermediate. I presume freshwater is used as the refrigerant for cost, environmental and safety reasons. (Any system which cools directly in the ocean especially if it uses some semi hazardous refrigerant would need to consider such issues, as well as maintenance and construction costs.)  Nil Einne (talk) 13:49, 15 August 2017 (UTC)


 * Salt water is not very gentle on whatever you put it into (pipes, etc.). Also, in some of the example applications you gave, the water will then evaporate and leave the salt behind, which is usually undesirable. Reclaimed water systems are what is generally used to produce non-potable water and reduce water usage. --47.138.161.183 (talk) 08:10, 14 August 2017 (UTC)


 * Salt doesn't tend to come out of solution until the seawater is quite concentrated. At high temperatures, the bigger problem is sulphates, as these form a hard scale that's hard to shift. Provided that brine isn't concentrated more than three times, and doesn't exceed 60ºC, it's not a big problem (see Evaporator). Andy Dingley (talk) 09:44, 14 August 2017 (UTC)


 * The salt doesn't need to come out of solution to be a problem. It acts as a catalyst to increase corrosion, such as iron rust.  Also, there's the smell.  Sea water often smells like fish, and many may find that unpleasant. StuRat (talk) 20:26, 15 August 2017 (UTC)
 * That's a vast over-simplification. It depends on the type of steel used. It depends hugely on the remaining oxygen content. Brine is typically (as the process that concentrated it usually deoxygenated it too) not a problem for corrosion in closed piping. Andy Dingley (talk) 17:03, 16 August 2017 (UTC)


 * . .  .  -- Jayron 32 12:11, 14 August 2017 (UTC)


 * Sea-water can be used for flushing toilets; assuming that the sewage system can cope with saline water. However, that means having two sets of water entering the properties, and is probably only worth it for new-build estates. LongHairedFop (talk) 18:12, 15 August 2017 (UTC)


 * A better solution may be implementing a gray water system. For example, the shower water can be used to flush the toilet.  I have such a system myself.  See the WikiHow page: .  No additional plumbing needs to be run to the house (for sea water) or from it (to desalinate waste water). StuRat (talk) 20:28, 15 August 2017 (UTC)


 * Another disadvantage to using sea water is that it implies the use of pumps, while freshwater from a higher elevation can often be gravity-fed. The cost of all those pumps and electricity is substantial. StuRat (talk) 17:09, 16 August 2017 (UTC)
 * no. Water systems always use Water towers that always have pumps, anyway. And, pumping account for a negligible amount in water price, for you need tremendous amount of water and height to generate a significant cost. Pumping 1 m3 100 m high only need 981 kJ, that is, less than 0.28 kWh. Obviously seawater would be used only close and not very high from the sea, with no significant difference with water pumped from nearby river (which level is also close do sea level for coastal cities), as is usually done.
 * In my city, they put the brand new wastewater treatment plant uphill, only scientific illiterates vociferated above energy waste of pumping. Gem fr (talk) 09:18, 17 August 2017 (UTC)


 * Most of the time, we don't really use water, rather, we use the "freshness" of water, and turn it into some kind of "impure" water, while the water itself is not consumed in the process. And, in this respect, seawater is usually the most unusable kind of water. So, you consider using seawater only when every other kind of water is either already used, or unavailable.
 * AND
 * In water management, capital costs far exceed running costs. So, establishing a special new piping for seawater would be much more costly, than converting seawater -- through desalination -- into water than can be used in the original, fresh water piping. Gem fr (talk) 09:48, 17 August 2017 (UTC)