Recent comments in /f/askscience

EmilyU1F984 t1_j4kqypw wrote

Reply to comment by [deleted] in Post exposure rabies shots protection? by [deleted]

You need to get your antibody titer checked.

There’s no other way to check whether a vaccination worked in causing immunity, and no other way to tell whether you still have sufficient immunity.

In most cases a fresh vaccine course will yield sufficient protection against infection.

Also: the bats do need to bite you. Any other contact doesn‘t risk infection.

If bitten depending on your local health care system they will either determine tigers to see whether you have sufficient immunity, or do a refresher course of the vaccination, with or without immunoglobulin depending on further circumstances (immunocompromised, vaccination a decade old etc)

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thataccounttho t1_j4ko5qo wrote

Reply to comment by fuscator in My 4y/o told me her dream about losing teeth without ever knowing it's a common dream. Are there any other examples of cross-cultural phenomena that centers on a specific narrative? by [deleted]

The inability to run dream is the only reoccurring dream that I have and it’s always really vivid. I often wake up thinking that I have woken from a coma or something and I’m now unable to run.

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mojowind t1_j4kmzg3 wrote

Reply to comment by Ordoshsen in How do we know that we are in a certain place inside our galaxy? and how do we know how big it is just by looking at the cross section we are in? by friday_panda

The Gaia satellite is able to measure parallax with an unprecedented precision. Parallax is possible for the thousands that can be seen with the naked eye, and potentially any star in the Milky Way which we have a line of sight view.

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holynuggetsandcrack t1_j4kjv5q wrote

Reply to How do we know that we are in a certain place inside our galaxy? and how do we know how big it is just by looking at the cross section we are in? by friday_panda

So this is a nice question, considering we can figure out a lot of things about other galaxies that seem so unfathomably far away it'd make sense we could figure things out about our own — right?!

Astronomy/astrophysics is an observational science. We do not have the capacity to carry out experiments by nature, of, well, being small humans, meaning we only learn about things by looking at them. What can we learn about our Galaxy looking at it? Turns out, not much.

We know its shape, that's very evident from just the night sky alone. We can observe the black hole at its center, but we don't really know a whole lot about black holes, so all we can say about this one for sure is the one thing we know for all the others: they're old! And with a certain degree of accuracy we can determine its mass, by looking at how other things behave and move around it.

Do we know the galaxy's age? We in fact do! We look at the oldest globular clusters we can find in the milky way, figure out how many heavier elements they have (particularly Be), and from then we can figure out how many stars existed before these and thus — the age.

What about the size and shape, and our position in it? This is difficult... We can look at Cepheids (special types of stars that change brightness allowing us to discern their distance and the distance of objects around them) on the other end of the milky way and determine how far those are, but this really is not accurate. It's like measuring a basketball court by taking the distance between two furthest players. Not very accurate is it? We can't know the way it looks, zero way to do this without stepping outside, and we can somewhat discern where we are...in comparison to other objects in the galaxy? This is also a very rough estimate.

In short, the only real things we can know about the galaxy is the type and age. We can figure out a whole lot about objects in it though. :)

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CrateDane t1_j4kg8y3 wrote

Reply to comment by Furrypocketpussy in Can a recessive gene become a dominant gene? If so, how long would it take? by Pretend-Recover-4418

Well no. Full-blown sickle cell disease only affects homozygotes, and as such is considered recessive. But the heterozygotes do still have a different phenotype than either homozygote in some ways. That means in those respects the allele is not recessive at all. When it comes to malaria resistance, it's more of a dominant allele.

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