Wikipedia:Reference desk/Archives/Science/2013 October 25

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October 25

Soil dynamics

Am I correct in assuming that in soil dynamics, if measuring the total stress of any soil, you should multiply everything (sum of rho*h)by g/density of water? Or is this just for saturated soils? Clover345 (talk) 12:02, 25 October 2013 (UTC)

Mr Frosty cryogenic storage containers - replacing isopropyl alcohol

The Mr Frosty cryogenic storage containers for controlling the rate of temperature change when freezing cells (to 1 C/min) require that the IPA is changed every five uses. Why? What happens during each cycle (we freeze to -80 and the next day to -150 then let the container return to RT). --129.215.47.59 (talk) 19:06, 25 October 2013 (UTC)

You cool the container to -150? Manual seemed to say take the samples out at -80 and place them without container in the cooler... Forming of peroxides could be a reason for the regular IPA change, very unlikely I think but in theory there may be some risk because there's air in the container. Water absorption from the air, contamination of any kind. Evaporation or other losses... They don't want to be liable for accidents, so they may have picked the lowest number acceptable for customers (single use would seem wastful). None of the above would be a problem with five uses. Ssscienccce (talk) 04:10, 26 October 2013 (UTC)

I can't seem to find a reference for this, but I have always been told that it was specifically to prevent water absorption from the air, which would change the physical properties of the liquid and hence the cooling rate. Very cold alcohol absorbs water quite rapidly as it induces condensation of water vapour from the air. This is the same reason that one should not store a large stock of ethanol or isopropanol at -20 for DNA precipitations - when you open it to withdraw an aliquot it will condense water vapour and become gradually more and more dilute. P.S. I wouldn't classify a Mr Frosty as a storage container. Some people seem to think that it is one in my lab and it is most annoying when freezing down cells to find all the lab's Mr Frosty's are at -80 being used as storage containers! Equisetum (talk | contributions) 17:52, 27 October 2013 (UTC) p.p.s Although ethanol at -20 is not a good idea in the lab, gin at -20 at home for G&Ts is a very good idea indeed Equisetum (talk | contributions) 17:54, 27 October 2013 (UTC)

Sooo.... what does the fox say?

http://www.youtube.com/watch?v=jofNR_WkoCE — Preceding unsigned comment added by 24.45.120.97 (talk) 17:40, 25 October 2013 (UTC) (Seriously) — Preceding unsigned comment added by 24.45.120.97 (talk) 17:41, 25 October 2013 (UTC) — Preceding unsigned comment added by 122.111.243.217 (talk)

Here's a sample of a fox utterance or vocalization: [1]. They make a lot of different sounds. Here's another video that describes and demonstrates a few other vocalizations: [2]

(But really, no one knows :) SemanticMantis (talk) 02:31, 26 October 2013 (UTC)

The ones around the London suburbs mostly seem to make a noise like a dustbin being knocked over ;-) Seriously, they do make quite a bit of noise sometimes - including the 'human scream' sound, which isn't something you want to hear in the middle of the night. AndyTheGrump (talk) 02:45, 26 October 2013 (UTC)

Apparently I've been living under a rock somewhere!122.111.243.217 (talk) 08:10, 26 October 2013 (UTC)

You will find the answer to your question at [3] and [4]. They are mostly high pitched barks and howls Richerman (talk) 10:17, 26 October 2013 (UTC)

If it's not clear from the comments, the OP linked to a very cute and catchy pop song along the lines of a children's book on animal sounds, with a great role for the fox. Interestingly, ducks say quock according to the song. I can't wait to show it to my niebles. μηδείς (talk) 00:13, 27 October 2013 (UTC)

You mean your niblings [5], right? SemanticMantis (talk) 13:52, 27 October 2013 (UTC)

Yes, nieble is the diminutive form. (Good catch--was unaware I had been anticipated.) μηδείς (talk) 17:21, 27 October 2013 (UTC)