That's a requirement for a test I'm going to take. I tend to learn better with well designed, reasonably comprehensive books that don't treat me like a dumbass (not as a genius either!).

Please notice that I'm not asking for websites, interactive platforms, videos, or whatever, but about books, preferably ones that I can study on my Kindle (so PDFs are not ideal). I know all the major websites but I just can't follow them.

I can pay very small amounts but I'm pretty much unemployed in a third world country so free is always better.

If there are requirements to understand such books, kindly inform!

I finished school more than 20 years ago and I was not a good student. But I'm kind of a decent learner now that I have a diagnostics (ADHD).

Thanks a bunch!

EDIT: guys, I am actually a beginner in the sense that I literally know little to nothing about the subject! I'm also not a math wizard. Advanced suggestions are appreciated but also entirely useless. This is also for a test, so, beyond a very brief introduction, general understandings on the Neil DeGrasse Tyson level is also of little use for me. I don't need to understand the beauty of the cosmos, I need to pass a test. Thanks!

I was always familiar with tornadoes living close to or in Oklahoma for a vast majority of my life. However, with the odd weather patterns we’re seeing this year producing severe weather, I’ve gone way down the rabbit hole. Watching weather livestreams, subscribing to chasers, the works. Has anyone else been on the bandwagon?

Does there exist a function that does not include any trigonometric function in its definition that has similar properties (periodicity, for instance) as trigonometric functions? I can't think of any, and this strikes me as a bit surprising.

Edit: I thought of a simple answer: piecewise functions can achieve this!

Greetings Folks, I apologize if this is the wrong spot for this but I'd like to cast a net to see if I can get any additional thoughts or help.

I recently started a new job as NGS Library Prep Tech - sadly I had only begun training on this briefly at my last position but only got an introduction to Speed/Mag Bead clean up. I was hired because the lab is growing quickly and has had issues with organizational stuff in the past and that is my strong suit (my last position I did a lot of clonal DNA / miniprep stuff as far as the wet work went).

The person I was replacing at my new job was only there for two days and didn't really help a whole lot other than hand me a haphazardly written protocol and said "practice by cleaning ladders at different bead concentrations and running them on a gel."

Did that and was told they look good.

Fast forward to using actual samples: There were a set that needed to be redone because the final pool was lost. When I did my first qubit quants after the post PCR speed bead clean up I noticed that the quant concentrations were ~80% less than what they had been previously.

Today I have some remaining sample that I can push through PCR, my plan is to quant 8 out of the 53 samples of the pre / post PCR plate and then again after I do clean up.

As far as clean up goes I had been trying to do the whole plate at once, but I'm going to go back to just completing a column at a time to ensure my timing is better.

Are there particular spots in the Speed / Mag Bead clean up process that I should be aware that I could be washing away / losing DNA?

Do people have any tips on how to be more 'sure footed' in this process?

Ways that I can better practice and say "yup, I've got this!"?

Thanks for the help, and if this should be posted somewhere else please let me know, but as this is 'science' related I thought it fit best here.

I am looking for practical ways to prove the Earth is round using materials accessible to the average person. I have zero interest in disproving Flat Earth folks.

I am inspired by Dan Olson's (Folding Ideas) excellent video where he is able to do this measuring the curvature of a lake near his home that has a very specific geography that lends itself to this sort of experiment. I've seen all sorts of ways to prove this measuring shadows and poles, using gyroscopes, etc. and wanted to know if there are any practical guides for proving once and for all that the Earth is round for yourself relying on nothing more than experimentation.

What I'm not looking for:

• Math relying on flight times/charts
• Video/picture evidence
• Deductive proofs built on agreed upon premises
• Expensive tests
• Extremely time consuming projects
• Underwhelming results (relying on a probabilistic argument for a round Earth from the evidence.)

What I am looking for:

• Practical experiments
• Things I could potentially do without spending much money
• Tests that aren't largely comprised of accepting someone else's research
• Potentially math-heavy evidence
• Results that are strong and conclusive

I've thought of finding some easy to test version of Eratosthenes' proof using two poles. I've also thought about using a balloon and sending something to space like what is done in this Tom Scott video. Nothing seems well documented in such a way as for me to be able to follow it at home.

TL;DR: I think it would be a meaningful experience to have the power to prove the Earth is round by myself, for myself. I can only compare this desire to the desire a child with a telescope has when wishing to observe Saturn or Mars themselves for the first time. It's not to prove anything or to settle doubts, but for the personal value of independently observing this astronomical fact oneself.

Intro

Hello everyone,

@wanda-seldon has been giving us an introduction to quantum physics. For now, she will be given a short break to prepare new stuff. In the meantime I will be covering some classical mechanics, more specifically thermodynamics. In part 1, we need to work our way through some of the more dry concepts, so we can understand and appreciate the horrifying implications of the fun parts. So I promise, this will be the most verbose one.

Some of you may have briefly seen a version of this posted, that was due to me misunderstanding the schedule with @wanda-seldon. If you saw that one, I will mention I rewrote nearly all of it to be more readable.

Now, on today's agenda: The basics of heat, work and energy and how it's all related.

Previous posts can be found here: https://tildes.net/~science/8al/meta_post_for_a_laypersons_introduction_to_series

Important note

If @wanda-seldon in her posts mention "energy", it's most likely in the context of energy operators, which is a concept in quantum physics. I'm not going to pretend I understand them, so I will not be explaining the difference. We will cover what energy is in classical mechanics. So keep that in mind if you read something from either of us.

Subject

Summarized

What is heat? Using a lot of fancy words we can describe it as follows. Heat is an energy that is transferred between systems by thermal interaction. And what is work? Work is an energy that is applied in a way that performs... work. The combined energy in a system is called internal energy. This type of energy can be transformed or applied to other systems.

These are a lot of new words, so lets break that down a bit.

Systems

A system is just a catch-all term for something that can be defined with a boundary of sorts. Be it mass, volume, shape, container, position, etc. A canister, your tea mug, the steam inside a boiler, your body, a cloud, a room, earth, etc. They are all systems because you can in some way define what is within the boundary, and what is beyond the boundary.

In theory, you could define every single nucleid in the universe as an unique system. But that would be counter-intuitive. In thermodynamics we tend to lump things into a system, and treat it as one thing. As opposed to Quantum stuff that looks at the smallest quantity. Calculating every single water molecule in my coffee would be pure insanity. So we just treat my mug as the boundary, and the tea inside the mug as the system. And just so it's mentioned, systems can contain systems, for instance a tea mug inside a room.

Energy

Energy is some quantifiable property that comes in either the form of heat, work. It can be transferred to other systems, or change between the different energy types. An example of transfer is my coffee cooling down because it's in a cold room. That means heat has been transferred from one system (my mug) to another system (the room). Alternatively you could say my hot coffee mug is warming up the room, or that the room is cooling down my coffee. Thermodynamics is a LOT about perspective. An example of transforming energy types is when we rub our hands together. That way we convert work (rubbing) into heat. It's really not more complicated than that. An interaction in this case is just a system having an effect on a different system. So a thermal interaction means it's an interaction due to heat (like in the mug example).

This brings us to an extremely important point. So important, it's considered "law". The first law of thermodynamics even. Energy cannot be destroyed, it can only change forms.

Your battery charge is never really lost. Neither is the heat of your mug of coffee. It just changed form or went somewhere else. The combined energy of all types that is residing inside a system is called internal energy.

Heat and work

Let's say we have a system, like a room. And all windows and doors are closed, so no energy can leave. In this system, you have a running table fan connected to a power line, getting energy from outside the system. The table fan is making you feel cool. Is the fan cooling down the room, heating up the room, or doing nothing? Think about it for a moment.

http://imgbox.com/CKtQLLOQ

The first thought of many would be to think that this fan would cool the room down, it sure makes you feel cooler! But it's actually heating up the room. As we remember, internal energy is the energy inside a system (room, in this case). The fan is getting energy from outside, and uses this energy to perform work. The fan accelerates the air inside the room, and this accelerated air will evaporate some of your sweat, so you feel cool. But as we remember, energy cannot be destroyed. So we are importing energy into the system, increasing the internal energy. Some of the work from the fan is also directly converted to heat, since the motor of the fan will get hot.

So if we are not getting rid of any of this excess energy, we are increasing the internal energy. And therefore actively increasing the temperature of the room.

http://imgbox.com/SAtqk7YG

To use a more tangible example: Simplified, this phenomena is why green house gases are bad. Lets define earth as a system. Earth gets a lot of energy from the sun. And a lot of this energy will be reflected and sent back to space. Green house gases will reflect back some of this energy trying to leave earth. So instead of having a roughly equal amount of energy enter the system (from the sun, from us doing stuff, etc) that leaves out in space, we have an increasing amount of energy on earth. This, as a consequence, increases temperature.

Implications

Now, what are the maybe not so obvious implications of this?

Waste heat, from supplied energy or inefficient work is a constant headache in engineering. If we cannot remove enough heat, we will actively heat up objects until they are destroyed. Thats why good cooling systems are important in cars, computers, etc.

Whats next?

Now this was not so bad. In the future we will cover phase changes, equilibriums, entropy, the heat death of the universe and briefly touch upon engines. So thats most likely two more parts after this. After that @wanda-seldon will take over again.

I plan on doing one main part per week, but if something is asked that warrants a small topic I might do smaller ones inbetween.

Feedback

Something unclear? Got questions? Got feedback? Or requests of topics to cover? Leave a comment.

I would like to find a good Statistics course to do for myself, and also to recommend to others, down the road ... one that specifically focuses on risk, and the discrepancy between actual statistical probability vs humans' intuitive sense of risk.

I recall a quote, which The Interwebs informs me right now, came from Albert A. Bartlett ... "The Greatest Shortcoming of the Human Race Is Man’s Inability To Understand the Exponential Function".

Alternately, Mark Twain popularized (but did not originate) the saying "There are lies, damned lies, and statistics".

That's the kind of course I'm looking for, that focuses on questions like how much should we actually worry about supervolcanoes, asteroid strikes, Covid 2.0, WWIII, Trump getting re-elected, etc.

There are two parts to this. One, people often (naturally, human nature, how our brains are wired to handle Risk) obsess about a short list of risks in life that are overblown, or appear to be more of a concern than they actually are.

The other part is, some things have a very small risk of actually happening, but when considered in conjunction with the potential consequences (asteroid strikes, WWIII, global pandemic), are still worthy of aggressive efforts to prevent ... and people often focus on the first element (statistically unlikely) and dismiss or overlook the second piece (devastating consequences).

Anyway, stuff like that ... ideally an actual, hands-on MOOC-type Statistics course, but even a good youtube video or blog article would suffice.

As usual, thanks in advance.

Publication: Helping or Harming? The Effect of Trigger Warnings on Individuals with Trauma Histories.

Pre-print version (for people, like me, who don't have access to the published version): https://www.researchgate.net/publication/334380654_Helping_or_Harming_The_Effect_of_Trigger_Warnings_on_Individuals_with_Trauma_Histories