Jump to content

ScienceNostalgia101

Senior Members
  • Content Count

    125
  • Joined

  • Last visited

Posts posted by ScienceNostalgia101


  1. On 1/11/2020 at 5:09 PM, Huckleberry of Yore said:

    A lot of low carb treats contain "sugar alcohols" which I gather don't metabolize as sugar does, at least for some of them.  Do these count as sugars?  I'd guess yes but they don't count as digestible carbs.  I've wondered if you ate enough would you get a buzz.  Might have to eat several pounds so it's a non issue.

    Apparently there's digestive problems from them as well.

     

    https://www.healthline.com/nutrition/sugar-alcohols-good-or-bad#section6

     

    Not sure if it'd be worth it for the buzz.

     

    The issue with the corn syrup thing is that the federal government itself won't call it sugar. So why the impetus to refuse to in this context even though fructose is referred to as "a sugar" in biology classes?

     

    https://www.nbcnews.com/health/health-news/feds-say-high-fructose-corn-syrup-not-sugar-flna805762


  2. On 1/4/2020 at 5:01 PM, Sensei said:

    How about different approach: instead of searching for a way to increase power production, search for a way to reduce current power usage?

    I forgot to reply to this earlier. I'd like to take this opportunity to ask; should this be the same thread or a separate one?

     

    Because I can think of some things that blur the distinction between "increasing power production" and "reducing current power usage."

     

    For instance, suppose that instead of throwing paper waste away, one were to burn it for heat. There are two ways I can think of for this heat to be used:

     

    A) Put a metal tube above the fire that does not allow smoke to enter, but allows the heat energy to conduct through, so that enclosed air molecules can warm up from contact with this surface and enter any household to which this tube is connected, or...

     

    B) Just directly boil water above it and use it to cook food or brew coffee.

     

    Would either of these be more efficient; or less; than transporting everyone's paper waste to an incinerator that uses higher temperatures to generate electricity? (Efficiency of an engine; if I recall correctly, is a strictly monotonic function of difference in temperature between the hot reservoir and cold reservoir, correct?)


  3. So a lot of companies try to get around admitting to the sugar content of their products through special pleading. They'll refuse to count high fructose corn syrup as sugar, for instance, presumably by the fact that it's technically chemically distinct from sucrose.

     

    This raises a key question; how was sugar originally defined? Did the original definition include all things chemically counted as sugars, or just a narrower subset of them?


  4. Water is easily the most common oxide of hydrogen. Its two hydrogen atoms for every oxygen atom correspond to the 2- charge of oxygen and 1+ for hydrogen. I would think, if only for those reasons, "hydrogen oxide" would be the most appropriate name for it.

     

    To cap it off, other covalent hydrogen compounds seemed to be named that way. H2S, for instance, isn't called "dihydrogen monosulfide." 

     

    However, I always hear "dihydrogen monoxide" referred to as the name for water when people are using it to mock environmental scares. I see two explanations for this:

     

    A. They're actually that ignorant about this, which would make it seem rather hypocritical to then paint environmentalists that way, or...

     

    B. They're deliberately misrepresenting the way chemical names work to catch people off-guard, whether to make it sound scarier than water's actual chemical name would be, or to avoid allowing anyone an opportunity to think "hydrogen oxide, eh? Hmm... what is formed when hydrogen is burned in oxygen again?"

     

    Is there a legitimate reason H2S is more commonly referred to as hydrogen sulfide and H2O as dihydrogen monoxide, or am I onto something here?


  5. On 1/5/2020 at 3:52 PM, swansont said:

    You would need to know the magnification to know the angles. The angle between the two points is approximately the length of the island divided by the distance to it. (The exact equation would use the arc length)

    Magnification... as in camera magnification, or is there an equivalent for "field of view" in the context of eyesight?


  6. On 1/5/2020 at 1:07 AM, zapatos said:

    If you stop the fires, how will that impact that which is dependent on fire? Is the impact an acceptable tradeoff to the benefits of limiting fire?

     

    •  

    Again, a network of permanent firebreaks could isolate the fire to one grid square at a time (presuming it didn't spread) but that isn't denying them fire altogether. It's just having one grid square catch fire at a time. So they'd still replenish themselves with fire, just on a smaller (if more frequent) scale.


  7.  

    https://www.youtube.com/watch?v=y-4qqcCxD6g

     

    So the following video shows a method; involving hydroxides, silver nitrate, and ammonia, for depositing silver directly onto a surface.

     

    1. Could any excess silver (ie. not deposited onto the surface) be re-used?

     

    2. Could something like this (make the metal deposit onto the surface) be used with cheaper reflective materials, like aluminum?

     

    3. How cost-effective would this be, as a mirror-making method? Does it depend on whether it's a flat mirror, concave mirror, or convex mirror? Would this be good for creating especially large concave/convex mirrors if you already had a large surface onto which to make the silver deposit itself?


  8. So this parody of an old video game portrays a (fictional!) oil explosion on an island from a distance; and the resulting duration of silence before the noise. Obviously, if we were directly given the angle to one end of the island and angle to another we could use geometry to estimate this fictional island's length. But here we're only given the distance to the island (via sound delay) and the fraction the island takes up of the field of view.

     

    This got me wondering whether or not "field of view" can be used to estimate "range of angles" between the point of observation and the object being observed. For instance, is there a function relating what fraction of a field of view an object takes up to the difference, in angle, between a bearing to the left side of the object and a bearing to the right side of the object? Does it depend on what these angles are, or only on the difference between them?


  9. 6 hours ago, Ken Fabian said:

    It is more a case of people building homes in fire prone locations then expecting the environment to be made safe around them afterwards, ie prioritising human choice over the environment - mostly it is choice not need in nations like the USA or Australia. Active hazard reduction measures require funding, equipping and organising - and citizens can be complacent at the personal level and can vote against giving governments the authority or capabilities or funding needed at larger levels. Climate change is increasing the dangers and the challenges and the costs.

    I think this overestimates how effective fire breaks are. Under mild conditions and for cool weather hazard reduction fires they help contain fires with good levels of success. During dangerous conditions with major fires they are used where possible to fight fire with fire by 'backburning' back towards oncoming fires, but with only limited success - even when heavily resourced with firefighting personnel and equipment to prevent the fire jumping. Australia's fires are dropping burning embers that start new fires many kilometres  ahead of fire fronts.

    There is no simple let alone low cost preventative measure. Eradication of vegetation is neither feasible nor desirable. Management involves government and statutory authorities that need to be resourced. On the ground individual landowners are going to have some of what they consider their "rights" overridden to reduce the broader risks.

     

    Trouble is, cities that have a solid, pragmatic reason to be placed where they do also suffer the consequences of forest fires. (Fort McMurray comes to mind.) I can see why people who built their homes in the middle of nowhere could reasonably be considered at fault, but what about cities with plainly practical reasons for their location? Why is there not more of a movement to create large enough firebreaks to stop the fire? Or irrigation systems within those firebreaks that could be remotely activated to spray the embers?


  10. Forgot I even had this thread! Asked this for the purposes of Christmas-themed problems for my students. Realized that, tempting as a "Santa Clausius" pun would be, other  topics than Clausius-Clapeyron worked anyway.

     

    That said, I'm still curious, and I'm not sure I fully understand the answer. I assume what you're saying is that if the rate of change in pressure is proportional to the rate of change in entropy with volume... therefore that entropic processes like evaporation will have to change pressure in accordance with that proportionality, making the effect of being a dissolved substance evaporating same as that of being a liquid evaporating?

     

    In a nutshell, is that a "yes"?

     

    Also, while I'm at it, why is it called the Clausius-Clapeyron equation if Clausius only came into the picture decades later?


  11. I mean the latent heat of vaporization; as in, yes, it's still around, but more of it as potential energy and less as kinetic?

    15 minutes ago, Sensei said:

    How about different approach: instead of searching for a way to increase power production, search for a way to reduce current power usage?

    Households in hotter regions of the Earth significant amount of electrical energy use on air conditioning and refrigeration of food.

    Households in the colder regions of the Earth use significant amounts of energy to heat homes during the winter.

     

    Decrease of power usage for TV and computers has been already done by migration to LCD/LED/OLED and to laptops (from power consuming CRT and plasma).

    So, limit energy used for air conditioning and refrigeration, and you will get the same effect as increased power production, with increased demand for power.

     

    See an example of some e-books smart displays. Instead of using power for continuous sustaining display, energy is used only for switching different pixels between one page and another page.

    https://en.wikipedia.org/wiki/Electronic_paper

     

    Personally, I am for turning streets to one large solar panels new generation with built-in electromagnets. They could produce energy and immediately transport it to vehicles flying slightly above them due to magnetic repulsion between streets and vehicles. Mass of cars would be minimal without full size tank nor full size accumulators. Without friction with road, energy spend on acceleration would be much smaller than now. To decelerate/brake there could be used KERS or similar system converting kinetic energy to electrical energy.

     

    Sounds good, but sounds like it'd take a while to make such drastic changes to infrastructure, whereas climate change needs to be dealt with more urgently. Maybe something to think of after the climate crisis is resolved?


  12. This issue has long been an obsession of mine, since before I even really had an accurate understanding of what it was. I used to think embryonic stem cells came from aborted fetuses; yet I get angry when hearing others spread the exact same myth. (For the record, for anyone reading, they come from in vitro fertilizations or from cloned embryos.) To avoid falling into the same sort of trap as before, I want to make sure I know what I'm talking about amidst an issue left murky by controversy.

     

    A. One popular talking point against embryonic stem cell research is that because other stem cells have (supposedly) gotten better results. Firstly, aren't they supposed to be useful for different purposes than other stem cells are? Secondly, how much time and/or money has been poured into research with embryonic stem cells vs. any other type of stem cells?

     

    B. Another is that you can supposedly "program" non-embryonic stem cells to act like embryonic ones. I heard a lot about this about a decade or so ago when Obama was lifting funding limits on this research, but it hasn't been in the mainstream discussion much since. Have any of you heard any updates on the efficacy of this one?

     

    C. There is also discussion on the tradeoff between public and private sector embryonic stem cell research. The supposed benefit of the latter is that the taxpayers who object to it can wash their hands of direct culpability for it, by the fact that it isn't their money going toward it. The tradeoff, however, is that any private company that profits more from the disease than they would from a cure has a perverse incentive not to cure that disease. As well, any cure they do release, they can patent and exorbitantly overcharge for. Critics of public funding for embryonic stem cell research claim that private companies would be involved in this research anyway. Is this true? If so, why does the government give private companies public tax dollars, and why can't they just cut out the middleman and do the research themselves?


  13. Enough people prioritize the environment over human lives to prevent thinning and firebreak-grids? Where were these people when the Lac Megantic derailment was used as an excuse for pipelines? (Putting aside the use of trains for other dangerous goods than just oil.)

     

    Quite frankly, that kind of thing makes me wish they'd not only create permanent firebreaks but salt the Earth beneath them as well.


  14. 28 minutes ago, swansont said:

    How much water do you use each day for cooking?

     

    The energy is being absorbed here on the planet, so I don’t see how the heat island effect would be reduced. To reduce albedo the light has to be reflected out to space. Solar thermal would tend to increase absorption.

    Hmm... what about the fact that some of the thermal energy that would otherwise go toward increasing surface temperature instead goes toward boiling water? Would that decrease temperature while simultaneously increasing humidity? (Assuming some of the water vapour above each pot of food/coffee escaped into outdoor air before condensing?)

     

    As for me, I don't cook. I work in places that have food available and/or eat canned fish/frozen dinners/peanut butter sandwiches for protein. Perhaps not the healthiest approach, but it's what I'm used to.


  15. https://www.youtube.com/watch?v=ci8ZXxYDajQ

    So in this Southland scene, a stolen taxi is aimed directly at a police car and driven toward them for a head-on collision. The cops swerve to avoid this.

    I'm just wondering now; is there any way to deploy spikes in the front of police cars, with springs behind the spikes, such that the engine and/or tires of the vehicle in front of them can be punctured, while the springs absorb the impact so the car's speed doesn't change as abruptly as that of the vehicle in front of them? That way, if this sort of thing happens in real life, they can deploy the spikes instead of swerving and stop the criminal sooner.


  16. So we as a society have categorized weight into "underweight," "healthy," and "overweight." We assume there is an interval of weight that is healthier, in and of itself, than weight above or below it.

     

    However, what I'm left wondering is; how do we distinguish the effects of weight itself from the high cholesterol that often happens to; but does not always; correlate with it?

     

    I was once underweight. I tried to put on the weight by eating a lot of fatty foods; ones that happened to be especially high, however, in saturated fats. That left me with high cholesterol while I was still underweight. It stands to reason that one can be overweight with low cholesterol. Americans also eat a lot of foods high in saturated fat, so it stands to reason the overweight Americans will be more likely to have high cholesterol. So how, then, do they know that the "weight" is what's causing their health problems, and not, you know, the cholesterol that tends to go with it?

     

    Have there been any studies on people who became overweight by, let's say, overeating avocado? Overeating peanuts? Overeating fish? Or any other such foods that are low in saturated fat and high in unsaturated fat?


  17. Time and time again, some part of the world's forests are on fire. I've discussed in this thread the notion of a network of water pipes above the forest, and I've been told it's unfeasible. I'm not sure if that has changed, but in the meantime, I intend to focus on the other options.

     

    A. Would increased logging of temperate forests significantly reduce the amount of combustible material in the long run? I've heard it temporarily increases it before decreasing it; why is that? (I would assume they'd find use for the wood, if not by incentivizing paper use as an alternative to other materials, then by incentivizing )

     

    B. What if they created a large criss-crossed pattern of permanent firebreaks such that the larger "forest" is then divided into a set of smaller forests, such that only one of these smaller forests can catch fire at a time, such that the forests can still use fire to replenish themselves without presenting as much of a danger to human lives?


  18. On 12/30/2019 at 8:36 AM, swansont said:

    Thermal benefits from scaling (bigger is better) — you need a certain number of mirrors to efficiently heat your material, and then you need a way to produce electricity, which also benefits from scaling. This is why it's done at the utility scale, not the home scale.

    Having direct heat is only useful when it's cold. So only a few months of the year in some places.

    What about enough heat to boil water for cooking food? That's useful even when it's warm. Also, if every household had a concave mirror for a rooftop, more sunlight would be absorbed by the boilers and less would be absorbed by anything else. Wouldn't that reduce the urban heat island effect? Could it also reduce the city's albedo to below what that of the pre-existing natural environment would have been?

     

    As for hail being not a big deal to solar panel rooftops, how come it's such a popular anti-solar talking point? Engineering angle aside, would replacing solar panels with concave mirrors do more good to the pro-solar movement or more harm from a PR standpoint?

     

    EDIT: And in light of Australia's wildfires, should I bump the "harnessing the energy of forest fires" thread or continue that discussion here?


  19. number of my past posts relate to hypothetical alternative sources of electrical power. I'm wondering if it'd be more efficient (pun intended) to coalesce them all into one megathread, such that people could compare and contrast these hypothetical proposals. I'd like to reiterate all these proposals, and a few new ones:

     

    A. One common criticism of household solar panel rooftops is that they're vulnerable to hail damage. I'm not sure if there's some way to mitigate this vulnerability that the fossil fuel industry doesn't want us to know or whatever, but in the meantime, since thermal solar isn't as vulnerable to hail damage, would a better approach be to have some rooftop concave mirror and/or rooftop convex/fresnel lens, to boil water? (This might also be more efficient twofold in having a direct source of heat, instead of having to convert heat into electricity and then electricity into heat.) If fire safety's the issue, would it be worthwhile to have the water supply BE the convex lens; namely, a watertight (apart from some outlet/intake tubes at the top) roof filled with water, such that the point of convergence is some dark surface within this roof that happens to be surrounded by water?

     

    B: So lightning is a form of direct current, is it not? If so, does that mean that some device designed to attract lightning, and run it through some electrolysis device, would be able to convert its electrical energy into chemical energy?


  20. In introductory chemistry at university I heard of an equation called the Clausius-Clapeyron equation relating vapour pressure to temperature of a substance. I vaguely recall hearing it applies to other liquids than just water. What I do not recall hearing is whether or not it applies solely to substances in their liquid phase. Does it apply to solids? Does it apply to solids dissolved in liquids? Does it apply to liquids dissolved in other liquids?


  21. Let's say you're graphing some function... for simplicity's sake, some quantity over time. There's a time interval that needs to be skipped because nothing happens during that time interval. What would be the proper way to skip that interval on the x-axis? I've seen zig-zags, dotted lines, etc... and I would like to be filled in on what is the correct way. Thank you in advance.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.