I’n a fisherman so I notice that the majority of the fish I target are (obviously) predatory. With the exception of carp and mackerel, I can’t think of many non-predatory fish. Why is that?

It has been a long time since I have taken physics, but I believe my question essentially boils down to can a planet rotate around two different axes such that the north pole is always tilted towards the star? I understand that seasons are caused by the tilt of the earth causing the North hemisphere to receive more sunlight than the south hemisphere for half a year and vice versa. Would it be possible for a planet to orbit a star in a way that the axis is always leaning towards the sun? I believe this would mean that the planet is orbiting around one axis (such as north and south poles) as well as another axis perpendicular to the plane of the orbit allowing the north pole to always be angled towards the sun. Would the axis of the north and south poles have to intersect with the star for this to be achieved, or could the angle of the axis be angled above or below the star?

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Hopefully I explained that well enough for you to understand.

What's to stop sodium that was pumped out of a cell against the concentration gradient with a protein pump from coming right back into the cell through a channel or pore in the membrane?

for context my background is a single course of QM.

i read that the fine structure is cause by corrections due to relativistic considerations (along with spin contribution).

here's my issue: arent the electrons in the atomic structure standing waves? as in, they are not propagating, so there is no relative velocity between them and the frame of reference (the nucleus).

my understanding is that the electrons can't be moving because if they were then they'd be radiating due to moving through the nucleus' E-field, which they aren't. not to mention if they ARE in motion then they're also all moving relative to each other's E-field in a multi-e system.

so how can bound electrons both be stationary waves and at the same time require relativistic corrections? what exactly is behaving "relativistically" in this system?

I have seen some diagrams that are supposed to display osmosis that go against all my intuition when it comes to physics and weight etc., like fig 1 on this page https://www.imperial.ac.uk/be-inspired/schools-outreach/secondary-schools/stem-in-action/the-human-body/osmosis--activity/

The water seems to me to move to a very exaggerated height, at about double what's on the other side of the membrane. I can't find any pictures of this experiment being done in real life. Can somebody let me know if this is realistic at all?

According to this newspaper article, which references a journal article, new research points to a couple of trillion tonnes of silicate dust as the component of the impact in the atmosphere with the greatest impact on temperature due to reducing solar radiation transmission through the atmosphere.

That got me thinking about present day carbon sequestration efforts and silicate weathering, and my question is: in the years and decades following the impact, as the silicate dust settled out into land and shallow seas, and got rained on on land, did it chemically sequester enough CO₂ to affect the climate?

Most colanders have drain holes distributed in radially symmetrical pattern clumps, however the distribution of the holes within the clump itself sometimes isn't symmetrical. To better illustrate my point here is a handy diagram: Link

I don't know how common this is, however I've seen it on enough colanders that there has to be some sort of reason for it and its not just a random decision/manufacturing error. Does such pattern possibly create a slight whirlpool in the draining water, thus making the drainage faster? Has the reason for this ever been mentioned in a text before?

It is crazy to me that just a piece of metal would kill bacteria

Google was exceptionally unhelpful.

With the exception of the Mohawk & Champlain valleys, the mountainous valleys here on the eastern half of the country are typically thin and narrow with a river or stream surrounded on both sides by forested mountains and hills with maybe a thin strip of flat land with a small village or town on the banks of the river usually connected by one or two roads along either side of the river and maybe a rail line slowly meandering along the sharp and winding curves of the valley. By contrast from what I’ve seen the Rockies and Western Ranges seem to be dominated by wide expansive open valleys filled with dry grassland and prairie or at least they seem to be far more common than they are here in the East. Which seems counterintuitive as since the Appalachians are much older you’d expect erosion to widen the valleys as the rock nearer to the tops of the mountains would erode quicker than those at the bottom smoothing out the slope and increasing deposition of sediment at the bottom expanding the distances between both the starts and peaks of mountains and creating wider valleys? Why is this?

In geology (crystal settling), I have seen some equate settling velocity to 2𝑔𝑟^2(𝜌𝑠−𝜌𝑓 )/9𝜂 while others to 𝑔𝑟^2(𝜌𝑠−𝜌𝑓 )/18𝜂. I'm just too dumb to understand if there's a difference between these two.

Hi Reddit! We are biologists from the University of Maryland here to answer all of your bat-related questions.

Gerald (Jerry) Wilkinson is a professor in the University of Maryland Department of Biology who conducts research on social behavior, with emphasis on how genetic mechanisms may influence the outcome of evolution. He has studied several species of bats, including vampire bats, in the Neotropics and the US to understand cooperative behavior and communication. Recently, his lab has used DNA methylation to predict age in bats and discovered that extreme longevity, which has evolved in multiple bat lineages, is associated with changes in methylation near genes involved in immunity. Current projects aim to identify epigenetic changes associated with social stress, immune function, and sex differences in aging in bats.

Katherine Armenta is a third-year Ph.D. student in the University of Maryland Behavior, Ecology, Evolution, and Systematics program (BEES). She is studying one of the most abundant bat species in Maryland, Eptesicus fuscus, or the big brown bat, and its communication and social behavior within and across species.

Danielle Adams is a postdoc in the Wilkinson Lab at the University of Maryland. She is studying the interactions between stress, aging, and immunity in wild bats. During her Ph.D. (UMD '19), she studied sexual selection in phyllostomid bats, a diverse family of leaf-nosed bat species found in the Neotropics. Prior to studying bats, Danielle studied vocal communication and the use of imitation in wild parrots. She also holds a master's in conservation biology (Columbia University '10).

We'll be on from 12 to 2:30 p.m. ET (16:00-18:30 UT), ask us anything!

Other links:

• Proof!
• A recent news article in The Atlantic about the implications of Jerry's research: https://www.theatlantic.com/science/archive/2022/08/bats-hibernation-anti-aging/671083/
• Research page: https://biology.umd.edu/people/gerald-wilkinson
• Google Scholar page: https://scholar.google.com/citations?user=Yy5PenMAAAAJ&hl=en

Username: /u/umd-science

I'm trying to grasp this concept. All macroscopic objects are mostly empty space, so you'd think my hand would go through the cup I'm holding. But it doesn't, because of the Pauli Exclusion Principle (at least that's what I'm led to understand). Something keeps the atoms of my hand separate from the atoms of the cup.

But gravity pulls down at the cup...so if the atoms of my hand and the cup are kept separate, how come it doesn't slide through my fingers? What, at the atomic level, is going on there to prevent it?

Wikipedia says Sri Lanka was geographically separated from India in 1480 after a cyclone destroyed Adam's Bridge. Many online resources (including esa and Wikipedia) point to "Rameshwaram Temple Records" that says Adams Bridge was submerged in the said fashion. In Sri Lankan historical sources, as far as I know, all the contact between Sri Lanka and Indian states are mentioned as happened by naval means. Sri Lanka was always considered an island and there is evidence to suggest that they were connected by a land bridge in pre historic times. Are there any historical records to support the claims of Sri Lanka being connected to India as late as 15th century? If so, how did that affect the people on the two ends.

So (I think) I know how a fault creates an earthquake, the stress builds up until it’s released in an instant, causing a movement on the fault and an earthquake. But what exactly does it mean when a fault ruptures? And bonus question; what is a seismic cycle and how does it work? Any and all responses are appreciated <3

Like the classic intolerance to nails on a chalkboard, mine is squeaky rubber. Like wet shoes on a tile floor, balloon animals being made, and absolutely worst of all, my toddler chewing on his pacifier.

It is excruciating. It causes a horrible physical sensation in my ears, teeth, and brain. Like being electrocuted, vibrating, and kinda tickles in a horrible way. It’s intense and comes in waves for at least a minute after the sound stops.

Anyone else experience this or know why this happens??

When you plant a seed. How does the sapling know which way is up? No light penetrates the soil so it can’t grow towards light. Is it able to sense gravity? Is it temperature? Moisture?

Would it act the same as if you were to take it directly afterwards? I know that anti venoms can stay in the body for a decent amount of time - but search engines don't seem to be giving a straight answer to this. Yes or no. They all just say why and how antivenom works but I already know why and how I want to know if you can take it BEFORE and when the drawbacks and/or benifits of doing so would be. It's almost like noone's asked before. Either that or my "google-fu" is genuinely that terrible.

I was watching the Budget Museum's youtube video "Dinosaurs of the Mountains" and it was mentioning that there was an abundance of these Oryctodromeus fossils in the Wayan formation because they seemed to be burrowing dinosaurs which would be well preserved when their burrows collapsed. It got me wondering, how accurately can you date a burrowing animal if its burrow is going into older and older strata in the geologic record? Would you hope to find the "top" of the burrow or some sort of infill from a higher layer?

As far as I understand it, dingoes got to Australia about 4000 years ago, yet Australias small flightless birds, mammals, and reptiles, are all still around. Why didn’t they cause the same ecological upheaval cats are today?

As the title says, as I understand it the white star we see as yellow will eventually shift to a more Yellow/Orange star before turing into a red giant. But during it's Yellow/Orange phase, what will we see? Will it still remain the same hue since we see it as yellow anyway?

Not sure if this is the right place for this.

For context, it's for a book I'm writing with a post-apocolyptic high fantasy setting, the USA is just a metric I'm using for general sizing. If it's even possible. I know nothing about earth curvature or any of the equations that would probably be used to calculate this. After a quick google search, geographical center is Lebanon, Kansas (???).

Hello, so, I've noticed that in the past, for narrowband (up to 5Khz sound) analogue voice transmission the radio frequencies used were in the hundreds of Khz up several Mhz, wideband sound (FM radio) uses frequences of tens to hundreds of Mhz and modern digital wireless transmission uses radio waves in the Ghz range, with 5G FR2 going into the tens of Ghz range. The trend is clear - more modern methods of wireless communication use higher frequency waves, with less range.

Am I correct in assuming this is because at high frequencies, even if you only occupy a small portion of the frequency you still got a huge bandwidth? And using the traditional Long Wave, Medium Wave and Short Wave frequencies, just how good of a bitrate could be achieved if instead of transmitting sound a digital mode using all advances in modern technology (most modern modulation etc.) are used? I did read a bit about packet radio but I don't think hobbyist packet radio represents the absolute best possible given that it often uses decades old, straightforward technology.

When we look at 'flat' galaxies, I believe that we can tell their orientation relative to us. Some face us directly, some are edge on.

Is there any pattern to this that we can detect? For example, are the galaxies in certain galactic clusters oriented in a similar way? Or is orientation just random?

If it's not random, does that tell us anything about the initial conditions of the universe (angular momentum, for example)?

I thought about this while walking my dog today and had no idea which answer is correct. I'd assume that most scientific tools could only measure a Photon's velocity, especially when the speed of light was first discovered in the Michelson-Morley experiment, but if that was the case wouldn't the oscillation of a photon provide a small incremental boost to the overall speed of the photon? But if the speed of light does account for the oscillation then wouldn't the distance that light travels be less than it's overall speed?

I'm not sure what the answer to my question is, more than likely it's nonsense haha. Would love to be informed.

I get incredibly distinct and vivid memories when I smell something from my past.

Hearts are rather important to animals, and a "backup" would certainly be nice to have. Perhaps they are too important, such that mutations which would potentially lead towards an eventual second heart would too often be fatal and so we never see it develop?

Anyway, thanks for your time!

I've just started Goldstein's Sensation and Perception (11th edition) and have been reading through visual processing. So far, my understanding is that our eyes convert energy from the environment (transduction) and this beautiful electrical, chemical dance happens within us to give us what we perceive.

However, I also just read that simply having a memory of a particular object can fire the SAME neurons as when we actually see that object. Where are those memory-influenced neurons getting their energy from?

I also understand some neurons are self-excitable, but aren't those for more involuntary processes like heartrate?

The brain is incredible!

Thank you.