Wikipedia:Reference desk/Archives/Science/2012 May 15

= May 15 =

Surfactants
Which have the best cleaning property : anionic surfactant, cationic surfactant or nonionic surfactant? — Preceding unsigned comment added by 113.162.202.31 (talk) 02:59, 15 May 2012 (UTC)
 * I guess that would depend on what you are trying to emulsify. I assume you know the difference between the three types? (I do.) Plasmic Physics (talk) 06:22, 15 May 2012 (UTC)
 * There's no right answer, it depends on what you try to clean, and there's loads of products of each type, varying in strength but also in price, toxicity, temperature ratings,... Your choice would likely depend more on availability and price, given that the "strongest" cleaner may not be on the market. The use of phosphates in laundry and dish detergent has been banned in EU and some other countries, replaced by more expensive, less effective alternatives. Not only were they biodegradable, they even caused eutrophication (from Greek "healthy, adequate nutrition, development"). But it seems that water plants, algae and jellyfish are considered inferior forms of life. Ssscienccce (talk) 21:05, 17 May 2012 (UTC)

Proper Dimensions for Mortality Rates
Compare these two statements:

"XXXXX syndrome has a mortality rate of 8%."

and

"XXXXX syndrome has a mortality rate of 8% per annum."

Is it usual to express mortality rate per unit of time, e.g., "8% of people with this syndrome are likely to die within a year"

Or WITHOUT a dimension of time, e.g., "8% of people who develop this syndrome are likely to die from it eventually."

Thanks, Wanderer57 (talk) 04:19, 15 May 2012 (UTC)


 * Mortality rates for non-permanent conditions are often offered without a dimension of time. But if you actually dig into the literature used to cite the statement, you will always find time measurements or additional caveats buried in the methods of measurement, even they're not presented as part of the short conclusion. Someguy1221 (talk) 04:26, 15 May 2012 (UTC)


 * Agreed. For something like influenza, it's likely to either kill you, or not, in short order, while with a disease like diabetes, you might live with it for years before it finally kills you (or something else does).  So, flu mortality doesn't need to be broken up by year, while diabetes does (although the total mortality rate from diabetes is also useful). StuRat (talk) 05:57, 15 May 2012 (UTC)

how much farther does a giraffe see
Hi,

how much farther does giraffe see? I mean due to vantage. --80.99.254.208 (talk) 10:59, 15 May 2012 (UTC)


 * The article Horizon contains various methods to calculate the distance, but first you need to measure your giraffe! Roger (talk) 11:16, 15 May 2012 (UTC)


 * Right, I just popped out and held down a giraffe long enough to measure it. Turns out they're between 5 & 6 metres tall. Assuming an average of 5.5m, using the calculation from the Horizon article we get a 'distance to the horizon' for the average giraffe of 8.37 km. That's 3.67 km further than the average human (4.37km at an average height of 1.7 m), a little less than twice as far. - Cucumber Mike (talk) 11:42, 15 May 2012 (UTC)


 * Wow, that's dramatic. Like, "If I have seen farther than those who came before me, then it is because I am a giraffe."  — Preceding unsigned comment added by 188.6.70.25 (talk) 12:34, 15 May 2012 (UTC)


 * ...or stood on the shoulders of the giraffes before you. :-) StuRat (talk) 16:22, 15 May 2012 (UTC)


 * Maybe it's giraffes all the way down. Gandalf61 (talk) 16:25, 15 May 2012 (UTC)


 * Note that this assumes a perfectly flat (actually spherical) surface with no trees or other objects in the way. And, since giraffes are that tall to reach leaves on even higher trees, we can assume that there frequently are trees blocking the view. StuRat (talk) 16:24, 15 May 2012 (UTC)


 * You also have to make an appointment for your giraffe to see an optometrist, because he might not actually be capable of seeing clearly all the way to the horizon anyway. Roger (talk) 16:30, 15 May 2012 (UTC)


 * Apparently giraffes do have excellent vision. As for the question, why do giraffes have long necks, the answer is that they have smelly feet. (*rolling tumbleweed* .... but my inner child is rolling in the aisles) FlowerpotmaN &middot;( t ) 16:56, 15 May 2012 (UTC)
 * You mean hooves. — Preceding unsigned comment added by 165.212.189.187 (talk) 14:02, 16 May 2012 (UTC)

Magnetic moment of a neutron
How does the quark structure of a neutron acount for its magnetic moment?--188.26.22.131 (talk) 11:35, 15 May 2012 (UTC)
 * There is a Neutron magnetic moment article, but unfortunately it's not much more than a stub. Red Act (talk) 19:21, 15 May 2012 (UTC)
 * The individual quarks within a neutron generate their own magnetic fields. And so the neutron will have its own magnetic field that is the superposition of the fields of its constituent quarks, resulting in a measurable magnetic moment even though it has no net charge. This is similar to how an electric dipole can have an electric field even though it need not have any net charge. And that's as much as I can tell you, for I don't know how to calculate magnetic fields/moments in quantum physics, much less how to superimpose the fields within a baryon. Someguy1221 (talk) 01:28, 16 May 2012 (UTC)

Lemonade (Citrus limon × reticulata)
How do I germinate lemonade seeds, what do I need to do to produce healthy seedlings? I have decided to use a paste made from crushed wheat biscuts mixed with water as a growth medium. The seeds have already been dried, naturally of course. Plasmic Physics (talk) 11:44, 15 May 2012 (UTC)
 * I found citrus seedlings are quite hardy when they are planted/germinated in sandy well drained loam (buried around 2cm deep). Once they grow a bit, they can be transplanted into their final destination. Will need the advice of someone better at horticulture for this though. (BTW, why are you trying to use that particular growth medium? I would expect that It to just help bacteria and fungi grow causing it to sour and form a film on the roots. Also I am not sure how much extra benefit the seeds would gain from the medium as the seeds are quite big. Again, just OR and speculation) Staticd (talk) 12:38, 15 May 2012 (UTC)


 * Staticd's instructions on medium and depth are good. I see that you are in the UK. It is probably not warm/ bright enough there right now to get fast results outdoors (e.g. not enough degree days), but it should work, given that you don't let it get moldy or drop below 40 F. If you are less patient, you could sprout it indoors, and provide supplemental lighting. It is important to not let it dry out, but also not to keep it sodden. "Evenly moist" is what you're going for. Lastly, your choice of medium does indeed seem bizarre, and likely to end in a moldy mess. Did someone suggest it to you, or did you read about it somewhere? Even if you don't want to buy peat pots, or potting soil, sandy loam is a far superior sprouting medium than crushed biscuits. Good luck! SemanticMantis (talk) 13:22, 15 May 2012 (UTC)
 * I'm actually posting from New Zealand, I live in a multistory appartment building; I'm growing it indoors for now. Thanks, I'll try and find some sandy loam. Plasmic Physics (talk) 15:00, 15 May 2012 (UTC)
 * Growth media are better suited for bacteria, fungi or cell cultures. Germination is what you wantSsscienccce (talk) 13:37, 15 May 2012 (UTC)
 * Is my idea then completely unsuitable, or will it just impede their development? Plasmic Physics (talk) 15:00, 15 May 2012 (UTC)
 * I feel that it will impede their growth quite dreadfully (going by my experience with pots having insufficient drainage and attempts at fermenting foods to get microscopy samples) so please don't try this unless you have a good source or you want to experiment. (Please do tell us the results if you do try it, I'm quite curious). Citrus plants need a lot of sun, but florescent light should do just fine. (They use them in the growth chambers at my research lab. Staticd (talk) 15:21, 15 May 2012 (UTC)
 * It contains a lot of nutrients your plant cannot use, but molds can. Plants mainly get water and inorganic nutrients from the soil. I doubt they can absorb carbohydrates, they get their carbon from CO 2 . A seed normally contains enough energy to grow the seed leaves, and then photosynthesis takes over. I'm not saying it's impossible to grow in such a medium but they have to compete against molds for which this is the perfect substrate, and there's lots of spores floating around. That's why substrate for growing mushrooms is sterilised in a pressure cooker first. Ssscienccce (talk) 17:17, 15 May 2012 (UTC)
 * It's amazing what mould can do. I remember saving bread end-crusts, before throwing them on the lawn when I get the chance. I forgot about a particular collection, and when I finally remembered, I found that mould had completely turned it into green dust. I made the mistake of opening the bag it used to be in, it sent a stiffling, noxious green cloud into the air. I also noticed that bread kept in a bag and chilled, and then returned to room temperature, will mould faster than a bagged bread kept at constant room temperature. I think it has to do with the reduced vapour pressure, which caused liquid water to condense on the bread. Plasmic Physics (talk) 03:01, 16 May 2012 (UTC)
 * Please send us photos when those lemonade seeds grow. I'd like to see what type of carton they sprout: Wax paper? Plastic? ←Baseball Bugs What's up, Doc? carrots→ 01:45, 16 May 2012 (UTC)
 * I'm using a disposable plastic catering tray. Plasmic Physics (talk) 03:01, 16 May 2012 (UTC)
 * And another one bites the dust, eh Bugs? I liked it though. Richard Avery (talk) 07:25, 16 May 2012 (UTC)
 * Personal experience alert: about ten years ago, I managed to germinate three lemon seeds from a supermarket lemon by using a two-litre lemonade bottle. Cut it in half, fill about two-thirds of the bottom half with soil and/or compost (we have a fairly heavy clay soil where I live in the UK, but it didn't do any harm; I suspect sandy loam would be better), then plant your seeds in and wedge the top back on. Put it in a warm, sunny place for the seeds to germinate. If they need extra water, dribble some in through the top of the bottle. Eventually I planted mine in pots and kept them in a warm lean-to on the side of our house; they lived until they got too big to move around between summer and winter. Have fun, Brammers (talk/c) 10:08, 16 May 2012 (UTC)
 * Thanks.

Another question: are lemonades grown outside of australasia? Plasmic Physics (talk) 12:01, 16 May 2012 (UTC)


 * To be clear, "Citrus limon x reticulata" is one possible composition of the Meyer lemon. Is this the fruit being discussed here?  And have some people in NZ started calling them "lemonades"?  (Note as explained in the article, "Meyer" was the guy who introduced the original Chinese hybrid into the U.S., so I doubt our term applies there, at least)  But this has a poster saying that lemonades are much sweeter than Meyer lemons.  And this says limon x reticulata is more like a lime!  NCBI delivers nothing of note about Meyer lemons, but Google Scholar yields a source talking about a Citrus meyerii  But ARS-GRIN calls lemonade a "hybrid of unknown parentage"   The joking above reflects that in the U.S. "lemonade" is strictly a drink and is never used to name a type of fruit.  Clearly it would be much appreciated if some taxonomists would do a little molecular biology here! Wnt (talk) 15:28, 16 May 2012 (UTC)
 * Here's the definition of the "-ade" suffix. Lemonade or orangeade or anything-ade is a product of the fruit, typically a juice product. Calling the fruit itself something-ade seems rather weird. ←Baseball Bugs What's up, Doc? carrots→ 00:04, 17 May 2012 (UTC)
 * No, I'm not talking about the 'Meyer lemon'. The 'Lemonade' is a ligitimate name used by plant nurseries. From what I know, it was created a few decades ago in Australia. I've never had lemonade drink, I've had lemonade flavoured drinks before though, Lemonades taste like lemonade. Unlike ordiniary lemons, the Lemonade can be eaten as is by most people. (not that I don't enjoy a good lemon). Plasmic Physics (talk) 01:53, 17 May 2012 (UTC)

Help identifying moths
Found this hawk moth/hornworm on some sort of colocasia.

Thanks. Hope to make at least some of each set useful for articles once they have been Identified. Staticd (talk) 12:28, 15 May 2012 (UTC)


 * These appear to be the Theretra clotho, the wingless female Orgyia antiqua perhaps?, and the Glyphodes bivitralis. (Disclaimer: I am not a lepidopterist! But I do like these bugs. :-))--Modocc (talk) 06:41, 16 May 2012 (UTC)

relationship between telomere length and cancer risk
Hello,

I am writing a biology paper on inhibiting telomerase to fight cancer, and I'd appreciate some help in interpreting the literature that's out there thus far. I'm not a biology student, but I did this research for a general education biology course at my college.

My literature review is focusing on this study published by Terry earlier this year, which stated that there is no clear relationship between telomere length and cancer risk. However, that seems to contradict the findings of Martinez-Delgado and others, who did find that shorter telomeres could present a risk factor for cancer. Indeed, my lit review has found that scientists have hoped to develop cancer therapies that focus on telomerase inhibition as a way to target malignant cells, and such methods rely on a strong association between telomere length and cancer risk. I know that it's not unusual for scientists to arrive at different conclusions, but what bothers me is that I can't find any articles online that attempt to reconcile these divergent findings. For example, I couldn't find any reactions to the Terry study, which seems to have overturned much of the previous literature. Am I looking at the wrong websites or databases, or am I approaching this paper in the wrong way? 128.135.100.102 (talk) 15:57, 15 May 2012 (UTC)


 * Not an answer, but have those considering such a treatment considered the side effects ? The telomere length is important for all cells, not just cancer cells, after all.  While cancer cells reproduce more often, and thus will suffer from short telomeres sooner, all the cells in the body eventually will (except perhaps nerve cells which don't reproduce). StuRat (talk) 16:29, 15 May 2012 (UTC)


 * (aside to Stu:) Nerve cells do regenerate, in a few different ways. See Nerve_regeneration, Neuron, and Neurogenesis. The idea that they don't is just another incorrect "fact" they taught us in highschool ;) SemanticMantis (talk) 18:43, 15 May 2012 (UTC)


 * The lede in your first link says "...the central nervous system is, for the most part, incapable of self-repair and regeneration". StuRat (talk) 18:50, 15 May 2012 (UTC)


 * Sure it does. It then goes on to discuss a few different forms of regeneration that do occur. My last link says "Adult neurogenesis is an example of a long-held scientific theory being overturned." That's all I really wanted to point out. SemanticMantis (talk) 19:18, 15 May 2012 (UTC)
 * I was initially looking at the wrong study.. Anyway, the main or only difference I can see is that Martinez talks about age adjusted telomere length. The effect she found decreased with age, the highest OR was in women under 30. The ovarian cancer article gives a median age at diagnosis of 63, with 4.7% in women under 34. Maybe that explains part of the discrepancy, that the effect Martinez found would be smaller in Terry's study who grouped the subjects by telomere length instead of age? I believe some data could even support both conclusions, see Simpson's paradox. I also noticed that mutations in BRCA1 and BRCA2 genes were linked with an increased risk, and in the BRCA1 article there's a list of specific mutations depending on nationality; Is it possible that the relationship between telomere length and cancer risk would be related in some mutations, but not in others?  Ssscienccce (talk) 19:30, 15 May 2012 (UTC)


 * The papers are just simply too new to have received any responses yet, I think. Note that the Martinez-Delgado paper cites the Terry paper. Looie496 (talk) 18:22, 15 May 2012 (UTC)


 * Even taking both papers at face value, they are not contradictory, as they deal with different cell types. A critical tumor suppressor in one tissue may be completely dispensable in another. Someguy1221 (talk) 19:07, 15 May 2012 (UTC) Sorry, I think I read the abstracts too fast. Someguy1221 (talk) 20:08, 15 May 2012 (UTC)

It looks like both consider correlations between peripheral blood leucocytes and ovarian cancer. As is too often the case, it looks like the smaller study had the significant (p<0.001) result, and the larger found no correlation. But I wouldn't want to simply discount the role of telomeres, because the larger study found that variation in TERT. We'd have to get the full papers, pick over every detail of who was chosen for each study, consider the second author's discussion very carefully ... and even then, this is the sort of thing that might have to be resolved over the phone, if at all. Some questions in my mind would be if they were able to control in any way for the effect of cigarette smoking, obesity and so forth and if there were any technical differences in how the studies did it. The problem is, I doubt it's the shortening of the telomeres per se that will cause cancer; it's probably what happens when a short telomere is found, or when there's no telomere at all. So my gut feeling is that the length of the telomere is the distraction and those polymorphisms in TERT are closer to what you should be interested in. It seems conceivable to me that you could make a drug that would affect TERT and have no effect on telomere length at all, yet affect the risk of cancer e.g. by affecting cellular senescence mechanisms. Wnt (talk) 19:16, 15 May 2012 (UTC)

Here's a numeric example that would give opposite conclusions: 10 young women with short trlomere's: 8 of them have cancer (80%). with long telomeres 30 out of 40 have cancer (75%). The numbers for old women are: short telomers: 60/100 (60%) long: 15/30 (50%) For both groups long telomers give a lower percentage. If you take the totals: short telomers: 68/110 (61%) long telomers: 45/70 (68%). So Martinez would find that short telomers increase the risk for young (80% to 75%) and for old women (60% to 50%), while Terry would conclude that short telomers decrease the risk (61% to 68%). Ssscienccce (talk) 20:21, 15 May 2012 (UTC)


 * Thank you for all of your comments! 128.135.100.102 (talk) 03:49, 18 May 2012 (UTC)

Grasshopper in Zion National Park
I was looking for a page similar to de:Wikipedia:Redaktion Biologie/Bestimmung, but it seems that there is none. Anyway, I hope is the right place for my question.

I took a photo of a comely grasshopper and uploaded it to Commons. However, since neither me nor editors from de.wikipedia were able to identify the species, it is not very useful. I hope a biologist from the Southwestern United States may help.

Place: Zion National Park; time: August. --Leyo 21:23, 15 May 2012 (UTC)
 * I'm not a biologist, but it looks a lot like Melanoplus femurrubrum to me. Cf. this image, for instance. Deor (talk) 23:03, 15 May 2012 (UTC)
 * I'm no entomologist, or more specifically, I'm no orthopterologist, but that looks like a very good match to me. ;) Vespine (talk) 23:47, 15 May 2012 (UTC)
 * Deor, you seem to have hit the bull's eye. Thank you. --Leyo 07:32, 16 May 2012 (UTC)
 * Deor, you seem to have hit the bull's eye. Thank you. --Leyo 07:32, 16 May 2012 (UTC)