Science desk
< January 31	<< Jan \| February \| Mar >>	February 2 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

February 1

Human Respiratory system

Hi I want to ask you about that

The wall of left ventricle of a human heart is thicker than that of the right ventricle.Why?Give reason

Thanks Sawongam (talk) 06:15, 1 February 2017 (UTC)[reply]

Sorry, we don't do your homework for you. 2601:646:8E01:7E0B:1C2B:1B0E:6B82:7D00 (talk) 06:19, 1 February 2017 (UTC)[reply]

First of all please note a heart is not a part of a respiratory system but rather of a circulatory system. --CiaPan (talk) 07:35, 1 February 2017 (UTC)[reply]

And yet the heart's relationship to the respiratory system is precisely what must be considered to answer this question. ;) Wnt (talk) 15:33, 1 February 2017 (UTC)[reply]

@Wnt: To be pedantic, the heart's relationship to the respiratory system (and in fact not to the respiratory system in general, but to the pulmonary circulation) is needed to answer the opposite question: Why the right ventricle's walls are thinner. For the question about thick walls of the left ventricle one rather needs to refer do the systemic circulation. --CiaPan (talk) 19:57, 2 February 2017 (UTC)[reply]

To be pedantic, the question of why one is thicker and the other is thinner is one question, since each is relative to the other... ;) Wnt (talk) 21:31, 2 February 2017 (UTC)[reply]

Nope. This is an extension of the question. --CiaPan (talk) 07:53, 3 February 2017 (UTC)[reply]

Blood pressure within the right ventricle is 15-30 systolic; within the left ventricle 100-140. See ventricular pressure. People with higher left ventricular pressure may develop left ventricular hypertrophy, in which the thickness of the left ventricle increases as the muscle compresses against greater pressure. The same thing occurs in the right ventricle, though less often, as right ventricular pressure is determined by the health of the lungs rather than by systemic blood pressure. - Nunh-huh 21:56, 2 February 2017 (UTC)[reply]

Name for length of time that data is recorded for

(I'm not sure if this is a science, maths of language question, so apologies if this is the wrong place to ask this). I'm writing a report and want to say something to the effect of "the instrument recorded good data for two periods, A and B, plus a third period C where the values were incorrect". However, I don't want to use the word "period", because that could cause confusion with both the logging interval, and the periodic variation of the data. (Especially as part of the problem with the bad data is that the periodicity doesn't match reality). What would be a good alternative term to use? Iapetus (talk) 10:29, 1 February 2017 (UTC)[reply]

(edit conflict)I think "acquisition" is the best with a workaround here: Three acquisitions were made: A and B (where data was good) and C (where values were incorrect). After all, you are not really talking about duration but rather about the set of time (not sure if that's clear; if you can speak German, that's the same distinction as hour = Stunde/Uhr). In a more general context, "acquisition time" usually refer to the length of time of one experimental recording. Tigraan^{Click here to contact me} 10:39, 1 February 2017 (UTC)[reply]

Your wording would strongly risk implying there were only 3 recordings of data (i.e. 3 data points), not two time periods were acquisition of data was good and one time period where it was incorrect. Nil Einne (talk) 13:08, 1 February 2017 (UTC)[reply]

Would replacing "for two periods, A and B" with "during two periods, A and B" make the meaning clearer for your purpose? --100.34.204.4 (talk) 13:46, 1 February 2017 (UTC)[reply]

Maybe using typography and elaboration like this may make it clearer : "during two time periods, which we can designate 'A' and 'B'" --Jayron 32 14:25, 1 February 2017 (UTC)[reply]

Do you even need a noun? "The instrument recorded accurately between X and Y, and again when it was switched on from Z to W, but between I and J it had a problem..." But it depends heavily on your purpose -- why are you even reporting a bad run? Usually scientists just pitch out the mistake and talk about what was done correctly. That said, for a low-level report you might indeed include that. Also, if I were to use a noun I'd consider "run", "experiment", "trial", "replicate", "session" ... a lot of things might apply. Wnt (talk) 15:31, 1 February 2017 (UTC)[reply]

@Wardog Is the instrument some kind of Data logger (see the article that lists a host of devices)? If so, you may simply describe features of the log it produced. "Two out of three logs taken showed the expected periodicity of the data while the third is unexplained." Blooteuth (talk) 16:11, 1 February 2017 (UTC)[reply]

How about "two ranges of observations" or "two observation ranges"? Loraof (talk) 17:38, 1 February 2017 (UTC)[reply]

In scholarly works discussing things at many different and perhaps overlapping periods (e.g. time series analysis), we often use the word window for this kind of thing. E.g. "Data measured during the first window (w1=[t_0,t_1)) and window 3 ( w3=[t_2,t_3)) was good, though data gathered in the second window ( w2=[t_1,t_2)) was bad." We don't have one single article on it, we have many; see Window_(disambiguation) for a variety of related uses in science and engineering.

For an example in the scholarly literature, see here [1] "State Space Reconstruction Parameters in the Analysis of Chaotic Time Series - the Role of the Time Window Length". In my experience, "time window" is clarifying but not strictly necessary, depending on audience and context. Hope that helps, SemanticMantis (talk) 17:42, 1 February 2017 (UTC)[reply]

Thanks for the tips. I'll probably amalgamate several of the suggestions. To clarify (and answer some specific questions): the instrument was a data logger, specifically a tide gauge. It was set to record continuously for a period of 30+ days. Unfortunately, it malfunctioned. It logged valid data for about 2.5 days, but then stopped logging and didn't record anything for several days. Then it started logging again for about a week and a half, then stopped again. Then a few days later it started logging intermittently, but the values were invalid (both the amplitude and shape of the curve were implausible). I wanted to describe what happened so I had an explanation of why we didn't have data covering the required period. Iapetus (talk) 21:26, 5 February 2017 (UTC)[reply]

Windshield wiper fluid vs evaporative cooling

I had the standard -10F fluid in my car, and used it shortly after starting the car, on a +10F day, but it froze on the windshield. At first I thought the fluid might be bad, but then I considered that I was driving on the freeway when it froze up, so there must have been substantial evaporative cooling. So:

1) Do the (US) temperature ratings for windshield wiper fluid not take evaporative cooling into account ?

2) How much of a cushion should I add to account for it ? StuRat (talk) 22:29, 1 February 2017 (UTC)[reply]

It may just be as simple that much of the alcohol has evaporate whilst in the reservoir. Try some fresh stuff. The wipers should wipe it off before it freezes. Isopropyl alcohol can rejuvenate it and use a hydrometer for guidance.--Aspro (talk) 23:18, 1 February 2017 (UTC)[reply]

You would not have found the first product in history whose marketing team oversold its usable tolerances... --Jayron 32 00:19, 2 February 2017 (UTC)[reply]

For somebody who lives to criticize the answers of others, this is an exceptionally poor response. Not only did you not provide any refs, there's no attempt to actually answer the questions. StuRat (talk) 14:34, 5 February 2017 (UTC) [reply]

It may be relevant that the roof and windscreen of a car generally get colder than the rest of it at night, because they are facing/tilted towards the night sky from which there is very little radiated heat, whereas the side windows, etc., receive some radiated heat from the ground and, often significantly, from nearby buildings. If the incident occurred in the morning, before or within an hour or so of sunrise, the windscreen's glass may still have been markedly colder than the rest of the car and the ambient air temperature.

I've had similar experiences (though in my neck of the woods – the South of England – it rarely gets colder than +20F), so I usually check before moving off and if necessary wait until the heater has thoroughly warmed the windscreen. {The poster formerly known as 87.81.230.195} 94.12.94.189 (talk) 02:14, 2 February 2017 (UTC)[reply]

I've never seen windshield washer fluid freeze. Even on that day when it got to −49 °C (−56 °F). Conversions for those of us who have no clue what F is, −10 °F (−23 °C), 10 °F (−12 °C), 20 °F (−7 °C). CambridgeBayWeather, Uqaqtuq (talk), Sunasuttuq 16:39, 3 February 2017 (UTC)[reply]

I imagine the stores in Nunavut would try to return containers of washer fluid that arrive frozen solid. ;) Wnt (talk) 17:50, 3 February 2017 (UTC)[reply]

Here in Detroit, we have at least 2 grades of windshield wiper fluid, one (blue) rated to -10F and another (more expensive and green) for -35F. In Nunavut I doubt if they would try to sell the "light" version. They may even sell a standard version that's somewhat better than the best stuff they sell here. But then, our "light" stuff can be had for around US$1 a gallon, and I would guess you pay far more.

However, the more expensive stuff contains more alcohol, so the evaporative cooling might be even worse. StuRat (talk) 19:59, 3 February 2017 (UTC)[reply]

I wonder if in Singapore they just use tap water. Sagittarian Milky Way (talk) 13:08, 4 February 2017 (UTC)[reply]

Newton's Dog

Someone, tell me, what is the similarity between these three images? Is there any scientist related to this image other than Isaac Newton?

https://commons.wikimedia.org/wiki/File:Newton%27s_Dog_Analogy.jpg  — Preceding unsigned comment added by Bosstriples (talk • contribs) 22:50, 1 February 2017 (UTC)[reply]

Clearly a reference to this story : Diamond (dog)

I'm not sure the significance of the final image. It is a laboratory from a promotional screenshot of XCOM 2. Presumably it has something to do with the loss of experimental data, but I have not played the game, so I'm not sure. ApLundell (talk) 23:01, 1 February 2017 (UTC)[reply]

What I am pretty sure of is that that image is not Bosstriples' "own work" as claimed in the license info. It looks like he took a copyrighted screen grab from a video game and two copyrighted stock images by professional photographers, put them together, and claimed the work as his own. Well, Bosstriples, am I right? --Guy Macon (talk) 02:05, 2 February 2017 (UTC)[reply]

Here is a web page that uses the same stock image of diamonds, except uncropped: http://sites.psu.edu/siowfa15/2015/12/03/why-are-diamonds-so-special/ --Guy Macon (talk) 02:16, 2 February 2017 (UTC)[reply]

I deleted it as copyvio. DMacks (talk) 02:38, 2 February 2017 (UTC)[reply]