Questions in the Science & Nature category.
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I have been reading a little about formal grammar in the context of computer language parsing. I understand that a formal grammar G is defined as the tuple (N, Σ, P, S), where N are nonterminal symbols, Σ are terminal symbols, P are production rules, and S is the start symbol. N, Σ, and P are all finite sets. But what is it called if they're infinite? [more inside]
I am looking for examples of interactive dichotomous keys to use in a lesson on creating dichotomous keys. The few I've found have been... too cutesy and aimed at younger people. Do you know of any that are simple to follow, but not dumbed-down? [more inside]
I am trying to understand some statistical data in a piece dealing with a historical text corpus and am in over my depth, which doesn’t take much doing. I’d be grateful for a simple explanation of what’s going on, plus the technical terms for this phenomenon, if it is one. [more inside]
Is there a term for the phenomenon of imagining what a person looks like based on their voice? [more inside]
There's a park in the Bay Area that has a fish run to allow rainbow trout to migrate upstream. I've never seen fish migrating and I am oddly fixated on watching trout go up the fish run. Are there even trout in these streams anymore? [more inside]
Why do I suck at dictating texts? I can speak at the rate I can think (or faster, oops), and I can type (key and touch) at nearly stream-of-consciousness speed, but dictating SMS messages is always a really fraught process. I find that I stumble over words, need to start over, miss important points and basically just fail for anything more complex than "yes" "no" "cheddar please". Why is that? Is there a cognitive reason? Am I using under-exercised parts of the brain or something? [more inside]
I watched a documentary last year online about a pod of orcas residing off the shores of Argentina and their hunting and social habits. There was a specific scene where the calf of the pod wanders into a kelp forest and when it discovers it is separated from the rest of the pod, it remembers to stay still and call out for help. The rest of the pod then respond to the calls. What is the name of this documentary? I've been searching for too long but none of the videos that pop up have this scene.
I've been trying for weeks to identify a Florida tree for my mom from a photo, and I'm stymied. Can you help figure out what type of plant this is? Tampa, Florida. March 3, 2017. [more inside]
I'd like to build a shop light/tinker light out of cheap LED COBs, but I'm confused about how to size the driver. COBs have wattage, voltage and amperage ratings. To my understanding, to run 3 10w COBs, I would need a driver that puts out 30 watts. The voltage seems pretty straight forward, it's represented by a single number and the driver should be capable of delivering that. The amperage is where I get REALLY confused. [more inside]
After much lobbying, the council has planted some trees on the London housing estate where I live. Three years on, some are doing well, others less so. Some have been planted in grass-covered areas, and the grass has regrown up to the trunks. Could this be a major factor in why they're not growing very well? Is it likely to make much of a difference if I remove the grass around the base of the tree? Do I risk damaging the roots if I do?
I am trying to understand a statistical problem with resampling and variation, and I’m unsure of my terminology so it’s hard to search. I have a set of geographic areas with known populations, and I’d like to generate new areas with redistributions of those populations. I can assume that the population is evenly spread throughout the original areas, but this gives me numbers without any kind of confidence interval. What would I need to do to calculate variance or deviation for this problem? [more inside]
How do you preserve a dead beetle for long lasting ornamental value? [more inside]
Is there any scientific evidence that PMS/hormones make women unreliable/unstable? [more inside]
I lost/hid/misplaced an expensive and sentimental piece of jewelry several months ago. I really think I hid it somewhere in my house but I've searched and searched with no luck. Is hypnosis to remember what I did with it a real thing? Maybe I just lost it outside the house. I know it was in my purse at one point. [more inside]
What things should I bring along on a hike with some kids (age 9 & 12) who are curious about looking for cool rocks after a great demo in school? [more inside]
Is there a non-technical book that explains neural networks in sort of an introductory way for general readers? [more inside]
Please explain this ant (and other small insect) behavior I'm witnessing. [more inside]
After seeing the trailer for the latest King Kong movie, it got me thinking about why animals only get as big as they do. Is it because they evolve in an ecosystem and natural selection doesn't want you getting bigger than the food supply can managably feed? Is there a scientific principle that governs this that people have named? Is it a DNA thing? I guess I'm wondering what prevents gorillas from growing 100 feet tall. Could there ever be a mutation that allows this to happen? Thanks!
Dopamine floating around in your synapses will make you feel g<ood. But how? [more inside]
i want to put an inflatable pool in my small backyard. Then I want to fill it with water and lie on its surface on an inflatable chaise/raft thing. [more inside]