Recent comments in /f/askscience

fuckpudding t1_j2ycc4s wrote

The sponge is definitely carrying bacteria from dish one to dish two. But the soap + scrubbing is making the mechanical removal of food and bacteria much easier. Basically freeing it from adhesion to the surface of the dishes so that the final rinsing with water carries the bulk of it away and down the drain. I personally think sponges are gross and not good for cleaning things involved with eating. They harbor bacteria like it’s nobody’s business and you’re right to be questioning this. I’d recommend switching to a plastic bristled brush that you can fully rinse with before each dish or item that you wash.

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SignalDifficult5061 t1_j2y8xax wrote

It varies considerably for a number of reasons.

Transcript lifetime is generally regulated directly by degradation in a time dependent manner. There are regulated in many others ways as well including miRNAs, and probably at least half a dozen other things.

According to the below example the median half-life of a transcript was 7 hours, with a few mRNAs under an hour. This may be very different than for bacteria, or various cell types etc.

How many proteins are made per transcript before degradation is also liable to be very different for reasons like, for example, codon usage (rarer codons tend to have smaller tRNA pools) so it will take longer to translate and thus there will be fewer proteins, and any number of other things.

Database for mRNA half-life of 19 977 genes obtained by DNA microarray analysis of pluripotent and differentiating mouse embryonic stem cells

https://pubmed.ncbi.nlm.nih.gov/19001483/

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rrussell1995 t1_j2y76sg wrote

Soap contains emulsifiers which break down the membrane of bacterial cells. Emulsifiers are chemicals which allow oils (hydrophobic) and water (hydrophilic) to dissolve or mix in one another. They’re in everyday items such as ice cream paints etc.

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electric_ionland t1_j2y3f3w wrote

The groove is a V shape with 90 degree angle. Each side of the V encodes for a different channel. The result (depending on how they are configured) is that the up and down movement of the stylus give you the sum of both channels while the left to right movement give you the difference between them.

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mfb- t1_j2xueou wrote

An expendable Falcon Heavy can do that on a direct route (no course corrections needed) for $150 million or so.

A partially reusable Falcon Heavy or even smaller rockets can do it with fly-by maneuvers, but then you need course corrections on the way to aim more precisely, which means you need some sort of active spacecraft. The launch gets cheaper but the spacecraft will cost something.

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Weed_O_Whirler t1_j2xrwxj wrote

It doesn't take energy to apply a force. Think of a book sitting on a table. Gravity is pulling the book down (aka, a force pulling down) and the table is pushing up on the book (aka, a force pushing up). And it can just sit there forever. Obviously the table doesn't need energy to do that.

No different than the Sun keeping the Earth in orbit. The energy of the Earth/Sun system stays constant (assuming nothing else in the universe). The force the Sun is providing on the Earth isn't changing its kinetic energy (since kinetic energy only depends on the speed of the object, not its velocity), so conservation of energy doesn't get violated here.

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mfb- t1_j2xqps2 wrote

The Moon is about as reflective as asphalt, but various missions have left retroreflectors at their landing sites which are routinely targeted with lasers. They can measure the distance with a precision of a centimeter or so, depending on the experiment and targeted retroreflector.

Jupiter, Venus, Mars and Saturn and sometimes even larger asteroids need to be considered in these experiments, see e.g. this publication for a discussion. It's an extremely precise test of our understanding of gravity and the Solar System. Unfortunately it doesn't test MOND directly because a small acceleration from one specific object isn't enough (otherwise you could just say Earth is a billion objects providing a small acceleration each), you need a small acceleration overall. The Moon is not in such a place.

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Alkaven t1_j2xnbi6 wrote

My understanding of orbits is that if every particle in the universe vanished except the Earth and the Sun, the Earth would continue in its orbit, because it is in free-fall around the Sun.

My understanding of conservation of energy makes me think that this is impossible. I was told in HS physics that the Earth is constantly accelerating--not because it gets faster and faster, but because it's changing directions by going in a circle ellipse instead of a straight line. F=ma, so it takes force to change the direction. That force is provided by gravity... but here I get confused. Can gravity just provide this force forever? Does that not mean that it's generating energy (from nowhere)?

I'm ten years out of high school so I can't just raise my hand and ask the teacher :( I suspect that I knew the answer to my question at some point and have since forgotten it.

My Google searches somehow turn up all sorts of sources debunking flat earth theory, which is not what I'm trying to do here lol.

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kilotesla t1_j2xlq9l wrote

>low amplitude is only gonna excite the rods? High amplitude will allow the excitation of cones and at that point frequency will determine which cones are excited?

Yes, and yes, if that helps. Of course, the rods' response is not independent of frequency, but since there's only one type, you have no way to distinguish colors using them.

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