ScienceNostalgia101

Ah, so the wetter and more heavily it's packed down, the more like a floor it acts. Thanks!

Man, it is a good thing I didn't attempt snow diving in spring.

Am I to assume the tradeoffs depend on the scale on which they're being used?

For photovoltaics, I'm not sure industrial use would necessarily be any more efficient than household use, on a per-panel level, but for thermal!solar, it sounds almost like the reasons for higher efficiency follow from thermodynamics itself... larger array of mirrors mean more sun rays converged means more sun rays on the same area means higher maximum temperature meaning higher difference between warm and cold reservoirs of the heat engine, which from what I recall from thermodynamics is more efficient, all else held constant. How do the initial costs and maintenance costs of each compare, and how does that depend on the scale on which the photovoltaics and/or thermal solar are being used?
 

In light of the above, it makes sense that major solar installations go for the array-of-mirrors approach. But what about on the office or household scale? If one were to purchase a half-pipe to line with tinfoil for use as a solar collector, would it eventually pay for itself in terms of what you save on maintenance compared to, let's say, some solar panel? Or would a half-pipe lined with tinfoil cost more in maintenance anyway? What about if one intended to use the halfpipe solar collector not to produce electricity, but to heat water directly for household / office use. (Eg. Tea, coffee, cooking, etc...?) Would that be more efficient than using solar panel electricity for heat?

So in this Family Guy scene, Peter Griffin attempts to recreate Scrooge McDuck's dive into a vault of coins and it... doesn't end well for him.

While I presume Family Guy's take on such a dive is relatively more accurate than that of DuckTales, I also think back to a childhood hobby of mine called "snow-diving," in which I could jump from a tree or a back patio onto a large enough pile of freshly fallen snow and it would cushion my fall. Is a pile of freshly fallen ice crystals not also "many pieces of solid matter"? If so, what factors determine whether they cushion your fall or act more lie a floor?

https://www.npr.org/sections/goatsandsoda/2022/03/03/1083751272/striking-new-evidence-points-to-seafood-market-in-wuhan-as-pandemic-origin-point

Given how intertwined this is with stats, I was almost considering posting this in the math subforum. But since there were other elements to it, I figured I'd post it here. I'm open to re-evaluating my views on the lab leak theory, but there are still a few questions lingering in my mind.

A: They don't name the specific studies by name, and claim that said studies are just "preliminary"; does this mean they've yet to be published? If so, how will we know where to find them once they are published? Until then, how can we trust that NPR isn't just twisting these scientists' words?

B: For those of you more well versed in stats, does the studies' statistical reasoning (or at least, what their statistical reasoning is according to NPR) sound valid?

How much of a section of third rail needs to be shut off at a time? Is it a segmented shutoff as in from one station to the next? How are the passengers informed of which direction to walk towards? Does it take longer to walk to the nearest station than it would to safely secure a ladder in place from which passengers could climb down? Or would they be worried about liability if a passenger slips and falls?

As for knowing the landmarks vs. knowing the stations, maybe I'm speaking from my experience as a tourist in cities with subway stations, but looking up various landmarks online ahead of time and having a rough idea where to go almost "feels" more geographically intuitive than being certain you read the map of subway stations correctly. I don't recall ever missing my stop, but I do recall underestimating how much longer a London Overground from Euston to Watford Junction would take compared to a direct route. (Speaking of London, I would never have guessed stuff like the DLR would have been considered an eyesore until you pointed it out.)

But as I mentioned before, another benefit is scenery for scenery's sake. Is there any way of measuring the extent to which that appeals to other passengers?

So two tradeoffs came to mind recently... the tradeoffs between subways and elevated rail, and the tradeoffs between solar panels and thermal solar.

So I figured I'd put them in the same thread, in case any more come to mind, or in case anyone else has any they'd like to share.

So of the downsides I've heard of to elevated rail, the most common I hear of are the noise, and the temperature fluctuations causing rail defects. However, I weigh this against two advantages. One, you see the town outside your window instead of only the tunnel, which, scenery for scenery's sake notwithstanding, has the added benefit of you not having to pay quite as careful attention to the station announcements as to not miss your stop because you can spot landmarks that tell you how close you are to where you're getting. Two; and this is a little more speculative; if the train packs ropes or ladders, doesn't that mean that, if it gets stuck, stranded passengers can just climb down to the surface instead of having to walk along the tunnel track carefully avoiding the third rail? Those two advantages in and of themselves notwithstanding, I'm left wondering something else; would these advantages also increase ridership to the point of reducing traffic, and therefore, reducing noise from traffic? And as for temperature fluctuations, how heavily does that depend on the temperature extremes a town gets? Would a place like Honolulu be less vulnerable to them than, let's say, Chicago?

For thermal solar and photovoltaics, I assume a tradeoff might depend on the economy of scale. Photovoltaics, presumably, are as efficient on a per-panel level in household use as industrial use, as I don't see why else they would be designed to be compact enough to fit on a rooftop. With thermal!solar, am I to presume that the larger the solar collector, the higher the temperature, and therefore the higher temperatures and higher thermodynamic efficiency? How do the initial costs and maintenance costs of each compare, and how does that depend on the scale on which the photovoltaics and/or thermal solar are being used?

Is there any way to make the barbs made of something see-through that the mosquitoes may mistake for standing water? As in, that they think they're flying into standing water but they're actually flying into sharp objects blocking the standing water?

Presuming it's put out of reach of human beings who'd make the same mistake. Or at least with warning signs posted nearby...

For me it's partly because air travel is stressful that I wish I could just sleep through the flight. Theoretically I could do much of the same stuff I do at home; type on my laptop, play video games, etc... but for some reason it just isn't as enjoyable at cruising altitude, partly because I realize that is stuff I could do anytime. Theoretically I could make the most of my time in the sky by staring out the window at the scenery, but even when I do manage to get a window seat, with a viewing angle that doesn't make my neck sore (which quite frankly isn't often), the scenery sometimes feels repetitive when it's of nature, and like it goes by too fast for me to know for sure what I'm looking at when it's of civilization. (Especially when I'm fumbling with the binoculars because of said viewing angle.) Unless it's an especially familiar area, I sometimes feel like my time is better served just trying to sleep so I can make the most of my time on land instead.

I remember getting motion sickness on a smaller plane in a direct flight between small towns. For the return flight I asked around for how to avoid motion sickness, and when they said the motion sickness pills have drowsiness as a side effect, deep down I felt like it was music to my ears. I ate the motion sickness pills at the start of the flight, fell asleep partway through, and arrived at my destination feeling... still somewhat drowsy, but in a more relaxed, mellow way that's hard to describe, and most importantly not queasy.

. . .

Anyway, back on topic, I figure even if I didn't fall asleep on my flight anyway, I wouldn't mind gaming or watching movies on my cellphone (I usually transfer them to the cellphone from my computer before putting it in airplane mode) while lying down... or looking out the window while lying down, assuming there would be window bunks not unlike there are window seats now.

The evacuation-guidelines point seems the more interesting (and concerning) one. Bunk beds mean whoever has the top bunk (which, ironically, would have probably the best downward viewing angle for scenery assuming they are above the windows; guess passengers would book bunks based on what they prioritize) would probably have to be the last ones off, as the people at the bottom would only need to crawl out of bed rather than walking down the ladder. The time it takes the lower "floor" to evacuate would give the top "floor" time to wake up and figure out what's going on... now I'm wondering, would the time it takes the lower "floor" to evacuate be longer than however long it takes the equivalent percentage of passengers closest to the emergency exits to evacuate?

I forgot to account for the issue of standing water attracting mosquitoes. Would putting wire mesh in and/or above the rainwater collectors be at least somewhat of a deterrent? Even if so, would there be the issue of the mosquitoes coming for the standing water, and staying for the readily available humans when they can't get at the standing water? Conversely, if the wire mesh were to be barbed, would one be able to attract mosquitoes to the standing water only for them to impale themselves on the barbs and therefore reduce their population to that comparable or lesser than what it would be were the rainwater not collected?

Don't they in practice make more money from credit than from passengers anyway?

The same applies to cost efficiency as fuel efficiency... why isn't it at least as cost-efficient or more to have passengers lying down than to have them sitting up? Hell, if they could fall asleep on the flight there'd be less demand for in-flight food or beverages. (Or less use for them in the first place...)

As for falling out during turbulence... is there any way to strap yourself in that would spread out the pressure adequately that turbulence merely jolts you awake without actually injuring you, let alone throwing you out of the bunk? Or alternatively a way for the PA system to notify passengers of turbulence with adequate time to brace for it?

I've also heard of local laws against using front yards as vegetable gardens. Makes me wonder how much money public officials have accepted from the agricultural industry.

Your own source says "to a river or beach", not "to a farm." I was wondering what infrastructure exists to redirect water that's clean enough for farming, but not clean enough to directly ingest, to farms.

So a common criticism of air travel is that it's hard to sleep during it. One contributing factor to this is the seats. Indeed, people are stuffed like sardines into these planes, it's part of what makes air travel so efficient.

But if they had beds in lieu of seats, would it be physically possible to stack them in a manner that crams just as many passengers into just as small an amount of space, while allowing them the convenience of getting to sleep (or at least lie down) for the whole flight? How safely could bunk beds be stacked together while still allowing room for people to get out if they need to use the washroom or something like that?

So recent events got me thinking about the politics that led us here, including the 2016 election and Martin O'Malley's so-called "rain tax". It taxed impermeable surfaces that cause water to pick up pollutants as it flows, and further damaged his already not-so-hopeful career. While Vox is defending this tax (or at least criticizing flawed criticisms of it); and I get realize that there is often more to these issues than some buzzword will let on; what I am wondering is why there wasn't infrastructure in place; whether on a local or federal level; to actually collect rainwater so it could be transported to where it could be used. Seems a waste to just let some mere lawn absorb it in the first place. While I'm not sure whether rainwater is clean enough to drink (although I'm pretty sure small amounts of it have gotten into my coffee cups from time to time), it sure is desalinized enough to be useful for farming. Why not have a network of concave-up ellipsoids and/or half-pipes over and around houses to collect the rainwater, and a network of rainwater-pipes that provide water that's suitable for everything short of drinking it?

On a larger scale, why not put a concave-up ellipsoid over the sections of the Atlantic and/or Pacific oceans that are directly underneath the intertropical convergence zone? That way, you can pump or siphon water from these ellipsoids into a network of on-shore rainwater reservoirs, as well as reducing the severity of hurricanes by the fact that their freshly fallen rain has fallen not into a deep ocean but to a comparatively shallower pool from which some of the water is already starting to be drawn out. Or am I missing something here?

Thank you so much! I'll look into AutoHotKey as soon as I get a chance!

So I have a job that lends itself well to being multi-tasked with audio, and while this has allowed me to explore a variety of podcasts, I can think of a more practical use yet... to listen to all the text files I have saved on my computer but haven't gotten around to listening to them such that I know which ones to keep, and/or listening to audio of the scanned, printed copies of my old journals from one of my previous jobs.

I have scanned paper copies of those, but the programs I've found haven't been good for converting them directly to text, let alone text that can be subsequently copied into a text to audio file. As well, individual RTF files are a hassle to open one by one and copy into text to audio programs one by one. Is there any program that could merge several dozen RTF files, for which the company selling it to be can be trusted with my credit card information?

Again that leaves the question of how closely is closely... would it be physicists scrutinizing physicists, or something more specific like particle physics vs. fluid dynamics as separate fields?

So I've tried listening to various YouTube summaries of the peer review process, but thus far one thing they have in common is that while they all point out that the peer review process involves scrutiny from people in "related" fields, they don't specify how related is "related."

If for instance, your paper were on particle physics, would the peer review process include scrutiny from people specialized in other branches of physics? What about from other physical sciences, like chemists or geologists? What about people from non-physical sciences, like psychologists or sociologists? And what about people from the humanities?

Likewise, if your paper were interdisciplinary between, let's say, biochemistry and behavioural neuroscience, would it be subject to scrutiny from biochemists and behavioural neuroscience, or other branches of biology, chemistry, or neuroscience? (On top of the questions in the above paragraph.)

Overnight update: Cooked it on the oven for a half hour to be on the safe side (wasn't sure it'd still be safe to eat if I left it another day) and I still feel fine hours later. Whatever bacteria got in the food through that hole, at least they didn't alter it chemically. At least not in any significantly harmful ways.

Coming back to this thread a month later, with a follow up question I forgot to ask... whether I put in tupperwares full of ice cubes (wherein a flat layer of ice would presumably form at the bottom on partial thaw, and a flat surface on complete thaw) or a coin at the top of a container of ice, that still leaves the question; if something was only partly melted, does that mean that its temperature stayed at 0, and therefore that anything directly beneath it in the shelf below it in the freezer was kept at or below zero? Does it depend on how much surface area of the top shelf the containers of ice occupy, at least compared to the surface area of the bottom shelf occupied by the food items I'm trying to keep frozen?

Not sure if meaningfully distinct from the danger zone thread; feel free to merge them if it isn't.

So the other day I noticed that the tupperware in which one of my meals was stored had a hole in it. If that didn't get germs in it, then being startled enough by this to wind up dropping it on the floor; on the side the hole was on; surely did.

However, the meal looks otherwise good and I don't want to throw it out needlessly. If I were to take the food out of the tupperware, put it on a cooking sheet, and heat it in the oven, is there a temperature and/or duration reasonably certain to kill all harmful pathogens? And does this need to be done tonight or tomorrow, or would Sunday be fine?

5 hours ago, swansont said:

Where are you hearing this?

https://ask.usda.gov/s/article/What-is-the-2-Hour-Rule-with-leaving-food-out

As for tea... I'll look into making sure I find tea with paper instead of plastic bags. (Some of those teabags made strong enough tea to fill a teapot with enough strong tea for 3 cups, so it feels like a little bit of a waste to throw it out after only one use. Besides, a weaker second cup of tea means a gradually diminishing caffeine dose...)

So I'm hearing that the danger zone for food and beverages left at room temperature is 1 to 2 hours; 1 if the room is warm enough, 2 if the room is reasonably cool. But does this depend on the food item?

Suppose I had a cup of tea, and left the teabag in the cup for reuse later. Do I need to pour boiling water in within 2 hours or otherwise discard the teabag? If so, does the boiling hot water reset the cycle for another 2 hours, or does the fact that the teabag was at room temperature somewhat reduce it?

In "Beavis And Butthead Do America" the boys escape a kidnapper by prying open the trunk and jumping out onto the highway. They claim that it's safe as long as they "run as soon as they hit the ground. Now frankly, this particular claim doesn't make sense to me, it isn't consistent with what subsequently happened, and I presume there isn't even supposed to be even a kernel of truth to it. (Though I'm open to any case to the contrary!) However...

A. If they had some means (large slingshot in the trunk, etc...) to have the horizontal component of their car-relative velocity on exiting the trunk be equal and opposite the car's ground-relative velocity (presuming they could convince the motorists behind them to make way and/or safely come to a stop) would the boys' ground-relative velocity be logically equivalent to freefall?

B. If they had rollerblades or skateboards or some other pedestrian vehicle with them in the trunk, and hit the ground through those, would this be logically equivalent to having sped up to highway-speed levels on their own (presuming they have experienced this going downhill), and therefore enable them to gradually slide right toward the gravel shoulder of the highway the same as they would if using rollerblades or skateboards at highway speeds otherwise? If they hit the gravel shoulder, would they be able to avoid or at least reduce injury by leaning against their deceleration, or would they be doomed to go face-flat into the gravel no matter what they do? Would it be safer to just wait and let friction slow them down, and hope the motorists on the highway both notice them and care enough to slow down with them?

C. If alternatively, if the motorists decided to take the law into their own hands and brake-check the driver, what would be the most survivable position for Beavis and Butthead to be in? Would they be safer with their back, their arms, their leg, etc... lined up evenly against the front of the trunk, to keep to a minimum the distance with which any part of them could be accelerated forward relative to the car? Or would it be better to have their knees and arms bent so that when they are accelerated forward against the front of the trunk, they can at least let their bent arms and knees push against the front of the trunk and absorb some of the impact?

(DISCLAIMER: Obviously, I don't intend to try any such high-speed stunts myself and would not recommend anyone here do so.)

A: In anticipation of future power outages, (last windstorm didn't do it but the next one could) I've been stuffing the top part of my freezer with tupperwaves full of ice. I'm figuring that because hot air rises and cold air sinks, that absorption of heat by melting ice would both preserve my frozen food for longer and double as an indication of how safe the food is by how much of the ice has melted. Would everything below this ice-water mixture be kept at 0 degrees centigrade due to sinking cold air, or is there something I'm missing?

B: A little trickier is the question of how to keep items in refrigerator part well enough below room temperature for food not to spoil quickly, but also well enough above freezing so as not to damage items due to severe cold. Would putting tupperwares full of icewater at the bottom create a vertical temperature gradient? If so, how stable would this temperature gradient be?

(Sidenote: Why isn't it the norm in apartment design that freezers and refrigerators are installed on the wall, and have one door opening to the apartment and another to the outdoors to keep food cold during a power outage? Presuming some sort of wire mesh on the latter to deter thieves, that is...)