Can We Take Political Correctness Seriously Now? - <AUTHOR> http://nymag.com/daily/intelligencer/2015/11/can-we-take-political-correctness-seriously-now.html <comment><USER2> relevant pg essay: [http://www.paulgraham.com/say.html](http://www.paulgraham.com/say.html)

This is a complicated topic, but my take is that the downside of political correctness is a potential for a loss of absolute correctness, while the benefit is respect and erring on the side of not doing harm. Those things need to be balanced and we have do decide as individuals and as a culture how we make those trade offs.

<comment><USER3> There is a huge potential downside from political correctness. When ideas are not allowed to compete on their intellectual merit (because someone finds them offensive), everybody loses.

</comment></comment><comment><USER4> It never ceases to amaze[1] me that whenever the left gets close to getting their voices heard in any broad sense, you start seeing these sort of polemics attacking them for not practicing absolute tolerance and freedom of speech whenever and wherever they assemble. Yes, there are intolerant assholes on the left, same as with any large group of people, and PC/SJW culture is fucking stupid, no doubt. But compared to our national media in the large, it is small potatoes.

Maybe students are sick to death of the status quo eating their future and wrecking their society and poisoning the Earth. They have grown up in a popular culture totally dominated by a right-wing media machine, wholly owned by the ruling class and which has successfully kept the Overton window so damned narrow we can hardly have a conversation anymore. It is completely understandable that they would want journalists to get the fuck out, rather than letting them get away with yet another hit piece attacking them on style rather than substance and completely ignoring their message. Look at the coverage of anything from OWS to Ferguson if you're curious why the left wants to tear the national media limb from rotten limb.

[1] depress

<comment><USER5> > whenever the left gets close to getting their voices heard in any broad > sense, you start seeing these sort of polemics attacking them for not > practicing absolute tolerance and freedom of speech whenever and wherever > they assemble.

A lot of people want to see what happens when this particular culture group gets power. What will they do, how do they behave?

> wholly owned by the ruling class and which has successfully kept the Overton > window so damned narrow we can hardly have a conversation anymore. It is > completely understandable that they would want journalists to get the fuck > out

So the right wing is preventing anybody from having a conversation—but it's okay because you don't want one anyway?

> if you're curious why the left wants to tear the national media limb from > rotten limb

And replace it with what, exactly?

</comment></comment><comment><USER6> Freedom of Speech is a wonderful thing. Those who oppress it know not it's true beauty.

</comment><comment><USER7> What is political correctness but censorship?

</comment><comment><USER8> Slavoj Zizek is probably the philosopher best known for show how political correctness is an overall bad thing for society. His stuff is worth checking out.

</comment><comment><USER9> I like tuhaybey's take on it (in the comments).

</comment><comment><USER10> Seeing how the same author has been trying to sound the alarm on political correctness at least since the beginning of this year, it seems unlikely that we'll start taking political correctness seriously any time soon.

Questioning political correctness is the realm of right-wing kooks anyway.

<comment><USER11> > _right-wing kooks_

The HN guidelines ask you to edit name-calling out of your comments here, so please do. In this case the last sentence could be eliminated, since that's all it does.

[https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html)</comment></comment>


Rocket Science and the Law of Demeter - <AUTHOR> http://practicingruby.com/articles/shared/gulrqynwlywm

<comment><USER2> This is interesting stuff, but I'm having difficulty wrapping my head around some of it. Here are some thoughts.

(1) Prohibiting function return values sounds bizarre at first. It's like anti-functional programming -- _insisting_ on side effects. But eventually I understood the reason: a returned object might have methods called on it. This is bad because such objects are "strangers" (in the LoD sense); we should not talk to them.

I guess the point is that traditional OO and functional style do not mix well. You can do state-modifying OO stuff, or you can work entirely with return values; you mix the two at your peril.

Or maybe the real problem is the everything-is-a-mutable-object idea. Applying these ideas to programming in C++, we could return an int without fear, since there are no methods to be called on it. We could also return a const object (I think ...). In Python, we could return anything immutable: integer, string, tuple, frozenset, etc.

(2) Concerning error handling, I see that prohibiting return values (which also forbids raising exceptions, I guess), makes it difficult for a function to signal errors to the caller. However, I do not agree that such signalling becomes _impossible_. A method is allowed to modify its arguments; it can signal an error that way.

But I'm a bit leery of the idea that requiring every function to handle its own errors, will result in more robust code. The argument seems to be that, since you have to write the error handling at the same time you're writing the code that produces the error, you're more likely to get it done. I'm not sure of that. I think the main trouble with error handling is that it requires work, and most of us don't really want to do that work. If a certain discipline helps motivate one person to write proper error handling, well, good, but it may not effectively motivate another person.

To put it another way: these ideas make some kinds of error handling more difficult. Does making something more difficult help it to get done?

But I haven't really thought this particular issue through. Prohibiting error signalling is going to have significant effects on software architecture at all levels. Some abstractions will simply be impossible, since they do not have all the information necessary for the handling of their own errors. I'm not at all sure what these effects might look like.

(3) Then there are the timing issues.

> There cannot be tight synchronization, as the sender cannot tell if the > message is acted on or not within any "small" period of time ....

I don't get this at all.

<comment><AUTHOR> Hi, I'm the author of the article, but keep in mind that the work is based on David Smyth's ideas, and I haven't tracked him down to verify my own interpretation of things. Instead, I was just hoping to start a conversation, and I'm glad to see you've responded here. I'll do the best I can to answer to your questions...

1) Yes, exactly my first thought as well! I've personally been gravitating to a more functional-programming inspired form of OO, and so at first these ideas bothered me. But then I thought about it a bit, and it seemed like these ideas actually push things in the direction of Alan Kay's vision of objects: fairly autonomous entities that interact solely through message passing.

In such a system, the interesting stuff gets pushed up into the messages passing between objects rather than the state and functionality within the objects. This makes it conceptually quite different than functional programming, and probably has very different pros and cons.

2) Prohibiting return values does make a big difference to the way we need to think about error handling. I think raising exceptions might be acceptable for validating inputs, but for other kinds of failures, you would need to use a callback mechanism to allow the client to handle problems. This could be an argument you pass in, as you mentioned, or there could be a mechanism by which either the caller or some other object could subscribe to failure notifications. In any case, the object that caused the failure would be responsible for how to notify its caller, if at all.

I am not sure that the argument for doing things this way is at all related to trying to make things harder or for encouraging you to write error handling at the same time you write a function (although those may be side effects). Instead, I think that the point is to _centralize_ failure handling so that the responsible object takes care of things rather than expecting every caller to know all the possible ways things can go wrong. For the sake of brevity, I cut an example from Smyth's correspondence that perhaps I should have left intact. Hopefully it will help shed some light on this issue for you:

        >4. Since there are no return values, the objects need to be
        >   "responsible" objects: they need to handle both nominal, and
        >   forseeable off-nominal cases. This has the wonderful affect of
        >   localizing failure handling within the object which has the
        >   best visibilitiy, and understanding, of whatever went wrong.
        >   It also dramatically reduces the complexity of protocols, and
        >   clients.
        >
        >   For example, with POSIX file system calls, one needs hundreds
        >   of lines of code to fully handle all possible failures of the
        >   open() call. This code needs to be at every open() call in all
        >   clients, because the POSIX file system is not responsible.
        >
        >   A responsible object would deal with the forseeable off-nominal
        >   cases. Then all clients benefit.
        >
        >   Clearly, something outside of the responsible object may need to
        >   act if the responsible object cannot resolve a problem with local
        >   action. OK - then a wider scope object needs to be involved: the
        >   responsible object sends the problem message "up" to some object
        >   with broader visibility. True, this might be, in a trivial system,
        >   the client -- but the problem is reported as a different message,
        >   not a return value from the original message (don't think
        >   continuations, because we are talking distributed here).

SOURCE: [http://www.ccs.neu.edu/research/demeter/demeter- method/LawOf...](http://www.ccs.neu.edu/research/demeter/demeter- method/LawOfDemeter/Smyth/LoD-revisited2)

3) I stared at this "tight synchronization" statement for a long time too, and it wasn't clear to me until I realized that Smyth's primary interest was in developing guidelines that facilitate robust programming in distributed real time environments. The point he was making here, I think is roughly this: If you are not expecting return values from your functions, you can treat them as if they were all concurrent calls which immediately run in the background. You will never need to _wait_ for a response, because you won't be calling functions on return values if you follow his variant of the LoD. Instead, results will get pushed to you via callback mechanisms only, which means that an arbitrary amount of time can pass between the time you call a function and the time that you know it has finished, and you won't need to worry about your functions blocking execution. The Ruby example I show in this article does demonstrate these ideas, through the use of threading. In a language with concurrent objects, you would get this effect "for free".

If you enjoyed this article, you might also enjoy another issue of Practicing Ruby that is on a related topic. Please check out "Responsibility-centric vs. Data-centric design", by Greg Moeck: <http://practicingruby.com/articles/shared/lrwkumltjnxr>

Hope that helps! I'll try to keep an eye on the conversation here, but may not have time to continue discussing things until next week sometime. Still, thanks for sharing your thoughts.</comment></comment>


SpaceX Dragon Successfully Docked With The Space Station - <AUTHOR> http://www.forbes.com/sites/alexknapp/2014/04/20/spacex-dragon-successfully-docked-with-the-space-station/ <comment><USER2> Congrats to the SpaceX team, always inspiring.

The correction made in the article (5000 tons => 5000 lbs) shows the importance of having mental visualizations for basic numerical concepts.

5000 lbs of cargo is about an SUV. I can imagine a rocket carrying that up.

5000 tons of cargo is... a giant Wal-mart parking lot full of SUVs (2000 of them). Stacked, they'd make a tower of metal a few miles high. (How? Figure 6 feet tall x 2000 = 12000+ feet.)

Can you imagine a rocket carrying that up and dropping it off at the space station? Nope.

When numbers are just symbols, mistakes like this are easy to make.

<comment><USER3> > Can you imagine a rocket carrying that up and dropping it off at the space > station? Nope.

Yes! [https://www.youtube.com/watch?v=8Ia2N4vpaEo&t=284](https://www.youtube.com/watch?v=8Ia2N4vpaEo&t=284)

<comment><USER4> I was hoping this thread would have a KSP link ;)

</comment></comment></comment><comment><USER5> After 3 scrubs most of our non-critical colleagues left the cape, but the view of our payloads in the trunk after 2nd stage sep made it all worthwhile. It's amazing what SpaceX has been able to accomplish and reinvent in a business this risk-averse and I can't wait to see what's next.

</comment><comment><USER6> Any more news on the performance of the first stage recovery test? Elon Musk tweeted that it was successful but I haven't heard anything more detailed than that.

<comment><USER7> The two things that were new this time:

* The 3-engine deorbit burn worked; previously it was screwed up by uncontrolled roll preventing the engines from getting fuel

* The 1-engine landing burn, previously separately demonstrated by the Grasshopper and F9R test vehicles, worked for a rocket coming down from orbit

The remaining items:

* 3-engine burn to take the rocket back to the Cape from downrange

* Making everything safe enough to dare landing at the Cape, without killing anyone or destroying all the expensive ground equipment that's nearby.

<comment><USER8> As for the last item, it's not as daunting as it seems. Range safety is actually fairly comparable in either direction. The trajectory of the booster won't naturally head over populated areas and it will have to be adjusted until it reaches back to land. If, for whatever reason, the trajectory adjustment goes to far and the booster would end up landing farther back on land then the stage can be signaled to be destructed, which will screw up its drag coefficient enough so that the debris will just fall safely into the water. And that's a worst case scenario.

<comment><USER9> Another reason it's less daunting is that, by the time of the landing burn, there's very little fuel remaining in the rocket. On the way up, the rocket has to have enough fuel to power the 9 first-stage engines for 181 seconds, and the second stage engine for 412 seconds. (As well as fuel for the various return and landing burns.) So it will have over 2000 engine-seconds of fuel.

In the landing burn, it's powering 1 engine for maybe 10 seconds. So that's less than half a percent of the initial fuel mass - something that would make a potential failure a lot less dangerous.

<comment><USER10> Ten seconds seems like an incredibly liberal estimate. You need a pretty decent "margin of error" reserve. I'd wager we're looking at something more like 30-60s of fuel during the last stages of landing, at least. So let's call it something like 2-3% of the fuel.

<comment><USER11> I'd imagine it's nowhere near full power for most of that, as it's an empty shell of a craft and thus quite light.

<comment><USER12> The engine can only throttle down to about 70%. For the final landing, the first stage will only use the center engine (leaving the other 8 shut down).

Even with only one engine at 70%, the thrust to weight ratio is greater than 1. That means the rocket can't hover, they just have to time the burn perfectly so the speed reaches 0 at the moment it reaches the ground.

<comment><USER4> Why can they only throttle to 70%? Is that related to old-school turbopumps?

<comment><USER13> Most rocket engines don't throttle down well. The main reason isn't the turbopumps (although that can also be an issue) but combustion instabilities in the chamber and flow separation in the nozzle.

Nasa overview of liquid engine throttling:

[http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2010003...](http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100033271.pdf)

<comment><USER4> Exactly the answer I was looking for-- thanks!

</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER14> SpaceX/Nasa livestreamed the whole docking (sadly I was asleep at the time...).

I don't know if the whole footage is up yet, but this is a nice summary: [https://www.youtube.com/watch?v=3fDzvdEfSgc](https://www.youtube.com/watch?v=3fDzvdEfSgc)

<comment><USER15> Thanks for the link to that. "Free drift trickery", indeed.

</comment></comment><comment><USER16> You know, thinking over [https://news.ycombinator.com/item?id=7617720](https://news.ycombinator.com/item?id=7617720) I almost wonder why Musk hasn't set an interim step to Mars that involves space habitats. Right now SpaceX is probably the closest to making an economy based on

[http://www.bigelowaerospace.com/](http://www.bigelowaerospace.com/)

and [http://www.planetaryresources.com/](http://www.planetaryresources.com/)

working. If they get the 1st stage reusable it brings the bootstrap costs down significantly.

<comment><USER17> It's not clear that it's an interim step exactly. Mars has gravity, earth for radiation shielding and some resources to work with. I don't know exactly what SpaceX have in mind for a Mars mission, but I'd be surprised if it wasn't a variant on 'Mars Direct'.

</comment></comment><comment><USER18> They also tested the new replacement to grasshopper called Falcon 9R Dev

[http://youtu.be/0UjWqQPWmsY](http://youtu.be/0UjWqQPWmsY)

</comment><comment><USER19> any video of the landing of the 1st stage, which is not a test ?

or is spacex still using expendable stages ?

<comment><USER20> The Falcon 9 is still expendable. They plan to recover the first stage this year and re-fly a stage next year.

</comment></comment><comment><USER21> an awesome start for reusable rockets, amazing!!

</comment><comment><USER22> 9.

Nf

</comment><comment><USER23> Just do not watch gravity movie tonight. on a serious note, it's friggi' amazing and makes me feel proud of our race every single day.

<comment><USER24> I'm curious actually: what's more appropriate to say in such statements: species or race, or something else entirely? I'm guessing It's would be species, but I'm not an expert on biology.

<comment><USER25> FYI, "human race" has idiomatic usage in english.

[https://en.wikipedia.org/wiki/Human_Race](https://en.wikipedia.org/wiki/Human_Race)

</comment></comment></comment><comment><USER26> I am skeptical of SpaceX its future endeavours. They proved they are on par with government subsidized space programmes, but haven't done anything astonishing yet. I mean, they probably bought a majority of the tech from NASA or the Soviets and just made it work. Not that it isn't impressive, just that an actual own in-house rocket would have been more ground breaking.

<comment><USER16> Their rocket designs are in house -- unlike competitors (like Orbital or Lockheed Martin who use refurbed Soviet Era engines). The vast majority of SpaceX's equipment is designed, built and tested all in house.

<comment><USER27> RD-180 was designed in 1990-s, after break-up of USSR, and you can't just saw in half RD-170 to get RD-180. "Refurbished" usually applies to something used for some time already - not to the rocket engines, certainly not to RD-180 and NK-33, which apart from being fire-tested weren't used in flight.

<comment><USER16> You're right about the RD-180, I think those are still produced?

I think Orbital also has used the NK-33 and NK-43, which were all built in the 60s and 70s. Refurbished can also just mean "something that was sitting around for a long time and needed to maintenance to get up to working". Anything that sits around for 40 years is going to need some kind of work done on it before it's put in service.

Either way, SpaceX doesn't use them.</comment></comment></comment></comment>


A bot for Starcraft in Rust, C or any other language - <AUTHOR> https://habr.com/en/post/436254/ <comment><USER2> If you're interested in this, there's a 24/7 twitch stream of Starcraft AI competing against each other that you may also want to check out or participate in.

[https://www.twitch.tv/sscait](https://www.twitch.tv/sscait)

</comment><comment><USER3> Awesome work. Of all the Blizzard titles, Brood War has a special place in me. The LAN party spring/summer of '99\. We even had our ritual of getting our 'StarCraft water' and going to the bathroom beforehand so there were no interruptions during the series of matches.

Edit: Also, will this work with StarCraft: Remastered?

<comment><USER4> Looks like people have instructions for using BWAPI with remastered, so probably. [https://github.com/suegy/bwapi-mono- bridge2/wiki/StarCraft-R...](https://github.com/suegy/bwapi-mono- bridge2/wiki/StarCraft-Remastered-Setup-BWAPI)

</comment></comment><comment><USER5> The author is here. Feel free to contact me if you are curious about the project.

</comment><comment><USER6> What is the situation today with SC/BW/SC2 on linux?

I dont have Windows. Dont have the CDs. Dont have a discrete GPU on my laptop. Is there anything available for plain linux?

<comment><USER7> works fine with wine, I replayed through the campaigns recently with the HD version

</comment></comment><comment><USER8> Just in time for this month's Starcraft LAN party...

<comment><USER9> Where do I find one of these Starcraft LAN parties?

</comment></comment><comment><USER10> Dangggg. I've just started getting back into Starcraft hard with the remastered release. Such a great game, so many great memories!

</comment><comment><USER11> This is an interesting read! Does this scale to League or other games, especially ones that have strong EAC protection?

<comment><USER4> This is really just a tutorial on using an FFI to call out to BWAPI. You would need to have an equivalent API to BWAPI, or write it yourself, if you wanted to interface with other games.

</comment></comment><comment><USER12> On a related note, turns out the orinigal Starcraft was turned into a free download back in 2017

</comment><comment><USER13> the picture about North/South Korea was useless.

<comment><USER14> I enjoyed it</comment></comment>


So, you know how I think Jira is mediocre and fails at some super basic stuff? - <AUTHOR> https://mobile.twitter.com/livlab/status/1179134097060442113 <comment><USER2> You can do all that stuff using Confluence, which integrates nicely with Jira.

It's not perfect because Confluence is originally a wiki, and last time I used it there was no templating, so the common pattern was to use an existing page as a prototype.</comment>


Did Japan Just Beat the Virus Without Lockdowns or Mass Testing? - <AUTHOR> https://www.bloomberg.com/news/articles/2020-05-22/did-japan-just-beat-the-virus-without-lockdowns-or-mass-testing <comment><USER2> "Experts are also credited with creating an easy-to-understand message of avoiding what are called the "Three C's" -- closed spaces, crowded spaces and close-contact settings"

This makes sense. In the US and other countries, people have become obsessed with things like runners not wearing masks or people gathering at beaches or washing their groceries, but all of those things are extremely low risk. Evidence keeps piling up that outdoor transmission is very difficult and surface transmission is remarkably unlikely. The primary way to spread a virus via droplet transmissions is to spend a sustained amount of time around lots of other people in an indoor space. That accounts for virtually all of the super-spreader events and avoiding these activities is likely responsible for the vast majority of the reduction in the transmission rate during these lockdowns.

I think we're gradually moving towards a system of restrictions based on universal mask wearing when indoors and avoiding crowded indoor spaces altogether. Most other restrictions are likely not necessary to keep the transmission rate low enough to avert catastrophe.

<comment><USER3> Schools will have to be outdoors-only when they reopen in the fall. This will work great, for a while.

<comment><USER2> More time outdoors instead of indoors is always better. In Denmark, things like teacher meetings are supposed to be outdoors now, and there's rules around picking up and dropping off kids outside. But for kids n class, a primary strategy places have used when reopening is to have kids stick with the same group of ~10 everyday. In Denmark, they used museums and other public places as overflow classrooms to keep class sizes extra small.

</comment></comment></comment><comment><USER4> I live in Tokyo, and I just want to point out that the voluntary compliance with the "request" to limit how much you go out appears to be better than the compliance with legally mandatory lockdown in California, which itself is far better than most other states in the US.

Yes, "businesses from restaurants to hairdressers stayed open", but most of them that I've ever used living here closed. Almost none of our restaurants (meaning the ones we used pre-COVID19) are open, or only do takeout. None of the places my kids have ever gotten their hair cut are open.

So I think this article might be placing too much emphasis on what the government mandated, and not enough on what people and businesses actually are doing.

I was watching TV news and they were naming and shaming pachinko slot-machine parlours that refused to close — and it was like 4 of them.

<comment><USER5> We have some data: looking at Google Covid-19 Community Mobility Reports, here are the numbers for (Japan, California, US) compared to baseline:

Retail & recreation: (-40%, -47%, -30%)

Grocery & pharmacy: (-12%, -7%, -3%)

Parks: (-52%, -14%, +32%) (yes that's a positive sign!)

Transit stations: (-55%, -41%, -34%)

Workplaces: (-23%, -27%, -24%)

Residential: (+14%, +12%, +9%)

So this data more or less seems to confirm what you said, though with obvious caveats (e.g. looking at say county-level may overturn some of this: compliance in Tokyo may be less than in San Francisco county and about as good as Santa Clara county, along some dimensions).

</comment></comment><comment><USER6> We could do with HN's own patio11 to weigh in on the subject. He's been tweeting intermittently about it: [https://twitter.com/patio11/status/1260181776086925312](https://twitter.com/patio11/status/1260181776086925312) [https://twitter.com/patio11/status/1255879667271086081](https://twitter.com/patio11/status/1255879667271086081) [https://twitter.com/patio11/status/1255618267885924352](https://twitter.com/patio11/status/1255618267885924352)

"Some observations from a socially distanced walk around central Tokyo yesterday:

* less foot traffic than you'd expect on beautiful day in spring that was holiday, but still high

* 98% mask usage

* 95% of neighborhood boutiques shut down"

[https://twitter.com/patio11/status/1255091793130950657](https://twitter.com/patio11/status/1255091793130950657)

"How serious is the state of emergency? I heard it is not a lockdown?"

As of tomorrow, there is no McDonalds in the nation which will let you eat there."

[https://twitter.com/patio11/status/1254836838344175616](https://twitter.com/patio11/status/1254836838344175616) "This is the WSJ, and I'm just one guy who happens to be able to read Japanese, so weight appropriately, but the consensus of experts is we're at the brink of losing the capability to do emergency medicine over approximately half of the country." (in response to over-optimistic WSJ coverage)

<comment><USER7> Even a cursory google search is showing that many things in Japan are/were closed: [https://jw-webmagazine.com/places-in-tokyo-closed-due-to- the...](https://jw-webmagazine.com/places-in-tokyo-closed-due-to-the-novel- coronavirus-covid-19/)

This article is feeling like American propaganda trying to justify giving up on response measures in the US. The most charitable interpretation is that it's factually incorrect in a broad way.

<comment><USER8> Yes, the headline was rather shocking to me! What a misleading article, it's very disappointing.

I know folks in Japan and life is anything but normal there. They didn't need a "lockdown" because of Japan's strong culture of conformity, and people take recommended precautions seriously.

Restaurants closed, schools closed, parks empty, everyone wearing masks, lots of social distancing.

The scale of the public's participation vastly exceeds that of the west -- there are little to no "nay-sayers" or people ignoring the rules. It makes a pretty big difference, evidently.

Anyone speculating that "Japan did less than the West and had an easier time how bizarre" is missing the forest for the trees.

<comment><USER9> We don't have a lockdown because it's unconstitutional. The situation where there's no lockdown and non-essential businesses that defect against society by remaining open are financially rewarded is motivating talk of fixing the constitution to allow lockdowns.

</comment></comment></comment></comment><comment> Seb-C I live in Tokyo and I think the biggest factor is the individual sense of responsibility.

From the beginning (and it gradually started far before the emergency declaration), most people and organizations recognized their role and responsibility and did whatever they could do to help.

My company gave material and instructions about washing hands, gargling and improved the frequency of cleaning in february, and then switched to remove- working for everybody as early as march. The company managing my share house did almost the same and even increased the frequency of cleaning.

Shops set up barriers in front of the cashiers. Restaurants either decided co close or switch to sake out only. Almost everybody started to wear masks since the beginning. When masks were impossible to find in shops, my company somehow achieved to deliver dozens of masks to all employees. When I got sick they also helped me by delivering furnitures and foods to my room.

So many people from western countries that are always talking about freedom seems unable to do anything else than ask their government to forcefully lockdown everybody. A government is not omnipotent and cannot fix everything magically. Recognizing your role and willingly do whatever you can is the only solution. Here, the government only asks people to do things whenever it is necessary, and they do.

</comment><comment><USER10> Living in Japan, the handling of the virus has been nothing but disappointing. We entered "state of emergency" but besides schools and a few stores closing nothing has changed. It is less people than before but the trains and buses are still packed, there are lines at the supermarket, even fast food chains (for takeout) and convenient stores, and families now chill outside and meet other families because children are at home. Parks are filled with people and the governments response has consistently only been "please stay at home" which, based on my experience of doing grocery runs, got ignored mostly outside of the major areas like Shibuya/Roppongi. Some business like pachinko parlors flat out ignored the governments requests and the reply to that was "close down or we will publicly announce your name".

People that got sick weren't allowed to take the test unless they fulfilled some checklist someone came up with. People with pneumonia symptoms got turned away at hospital after hospital and instead asked to rest at home which also had an effect on the low number of confirmed cases.

Some articles of people that got confirmed coronavirus but instead of getting quarantined, asked to please not work and self isolate (<\- there are also reports of people that were sick for weeks but just continued working with a mask until they were no longer able to). Same for charter flights and people from the cruise. Some people just denied getting tested, so they went home directly.

I have no idea how Japan got away with this but it's true that we are much better off than other countries. The official numbers don't reflect reality a single bit, but I can't argue about the low number of fatalities.

<comment><USER11> Japan has pretty low rates of obesity and heart disease, that might be related to the low death rate from the virus.

<comment><USER12> Or perhaps the virus did not make way into hospitals or nursing care homes. That's what happened in Italy, with hospitals turned into infection centers. And hospitals have a significant number of people at risk in them. Same for nursing care homes.

<comment><USER13> This is the country with the most dramatically aged population though. I'm rather surprised.

</comment></comment></comment></comment><comment><USER9> "businesses from restaurants to hairdressers stayed open" is a weird way to describe a situation in which most restaurants are closed and many open ones have transitioned to takeaway only.

Source: I live in Tokyo

</comment><comment><USER14> There's so much analysis about why this happened or that happened, but I feel like these things are just incredibly sensitive to initial conditions. Some place has a million cases because five infected people flew in and went to a popular club. That place has few because one sick person arrived and just went to bed at home. There's not a lot of evidence that policy and response is causal.

</comment><comment><USER15> _Japan has tested just 0.2% of its population -- one of the lowest rates among developed countries.

Yet the curve has been flattened, with deaths well below 1,000, by far the fewest among the Group of Seven developed nations. In Tokyo, its dense center, cases have dropped to single digits on most days._

excuse me, but given that testing rate, how the crap do you know that 1. the curve is flat, 2. deaths are at any particular number at all or 3. case rates are in any digit range at all?!

<comment><USER2> If the virus had spread in Japan at the same rate that we've seen in Italy and New York, we would know it. We would see it in hospital admissions and the number of deaths.

If early antibody testing is correct, then we don't know the actual transmission rate or number of cases in _any_ nation. Though Japan may be even more opaque because of their astoundingly low testing rate.

</comment></comment><comment><USER16> Read through the article and it seems like Japan didn't do anything out of the ordinary besides using skilled contact tracing. I'm just guessing, but that makes it seem to me like something cultural or genetic helped them avoid the worst.

One of the comments in the article guessed it was their low obesity rate. Interesting stuff! I'm excited to see some write ups for every country once this plays out.

<comment><USER17> Mask wearing perhaps?

<comment><USER18> That's likely a very big part. There was a recent study which found that if 80% of a population wore masks, that would cut the COVID cases to about 1/12th of what it would be in a population that took no protective measures.

If only 40% were to wear masks, they found almost no benefit.

By "masks" they don't just mean N95 masks. They include surgical masks, scarfs and bandanas used as masks, and other homemade or improvised masks.

Here's an article about that study [1].

For those who don't want to make their own or improvise, masks are becoming reasonably available. Newegg, for example, has several sellers which a search there on "masks" will find [2]. This includes some with stock in the US ready to ship, with delivery in a week or less. I just bought 50 disposable surgical-style masks for $30 from this listing [3], and they arrived in just over a week. At the time I bought they shipped from the seller but since then Newegg is handling shipping.

I picked that seller because they shipped from the US. A lot of sellers ship from China. Many of those do have reasonable shipping time, but I have no idea if the US Customs and Border Patrol is still seizing and redirecting PPE supplies that cross their paths. I figured a shipment that was entirely domestic was less likely to fall prey to government fuckwittery.

Tom's Guide has been maintaining a list of places with masks avaiable, which they update frequently [4]. That was were I learned that Newegg had masks in stock.

[1] [https://www.vanityfair.com/news/2020/05/masks- covid-19-infec...](https://www.vanityfair.com/news/2020/05/masks- covid-19-infections-would-plummet-new-study-says)

[2] [https://www.newegg.com/p/pl?d=masks](https://www.newegg.com/p/pl?d=masks)

[3] [https://www.newegg.com/picotee-face- mask/p/0CE-02AC-00001](https://www.newegg.com/picotee-face- mask/p/0CE-02AC-00001)

[4] [https://www.tomsguide.com/news/where-to-buy-face-masks- and-c...](https://www.tomsguide.com/news/where-to-buy-face-masks-and- coverings-online)

<comment><USER19> I think first link really oversells the study it references, though.Key quotes, from the paper:

"The factor by which β was reduced was conservatively set to 2."

"Varying degrees of mask effectiveness are modelled by the mask transmission rate T and mask absorption rate A, which denote the proportion of viruses that are stopped by the mask during exhaling (transmission) versus inhaling (absorption), respectively. Weset T = 0.7 and A = 0.7 to model the use of inexpensive, widely available, and even nonmedical or homemade masks [...]"

So basically, they _assume_ certain values for how effective masks are, and then simulates the dynamics of the epidemic. Nowhere do they try to justify the specific values chosen.

I expect that the conclusions cited (if only 40% wear masks, there is little benefit; if 80% wear masks, total cases go down by a factor 1/12) to be heavily dependent on those assumptions, and so I would be cautious to read too much into it.

Link to paper: [https://arxiv.org/pdf/2004.13553.pdf](https://arxiv.org/pdf/2004.13553.pdf)

</comment></comment></comment></comment><comment><USER20> The rate of infection largely depends on the initial rate of growth within the country, which in turn depends mainly on cultural and environmental factors.

This spreadsheet

[https://docs.google.com/spreadsheets/d/1AeG07Bt1fOA- msWYb9jW...](https://docs.google.com/spreadsheets/d/1AeG07Bt1fOA- msWYb9jWAl_bdo2ThBea7t2NzjFp2to/edit#gid=0)

compares two countries, each starting at an initial observed death rate of 1.0 / million. (The rate of growth here is (1 + Rt / serialInterval) or about the average daily spread to others)

The first country has a higher daily growth rate and locks down immediately, starting a process that will have its final effect on the deaths per million in 18 days.

The second country delays lockdown by 30 days and needs to do far fewer changes to reduce the growth rate to 1.01, and yet it doesn't surpass the deaths per million of the first.

You can get an approximation of (1 + Rt / serialInterval) but delayed by about 18 days if you look at the ratio of total deaths between two days (will need to be smoothed due to reporting variations). If you want a more realistic model you can get the same thing by tweaking R0 and intervention strengths/delays at [https://covid19-scenarios.org/](https://covid19-scenarios.org/)

This is a simplification (since it assumes that the entire population is a spreader rather than those infected 3-6 days before) but the conclusion doesn't change when you make the model more complex, and it explains why different countries seem to be doing so differently. The initial rate of growth completely dominates any other factors.

This image generated with covid-scenarios: [https://imgur.com/a/BRpkb0I](https://imgur.com/a/BRpkb0I) describes the variation in infected depending on R0 given everything else is the same with 2.5 being the average, 2.0 the lower bound and 3.0 being the upper bound.

</comment><comment><USER21> Does anyone know if they wear masks more in Japan? That might make a difference.

<comment><USER22> Way more. More culturally accepted and practiced widely.

This[0] is early April, government representatives all wearing masks, a normal practice for Japan.

[0] [https://www.arabnews.jp/en/japan/article_14235/](https://www.arabnews.jp/en/japan/article_14235/)

<comment><USER23> Is it really? Do you live in Japan, or have visited? When I was there, only sick people (even from a cold/flu) wore masks, to prevent the spread of disease.

That's still "more culturally accepted and practiced widely", but it was far from some claims I see that "everyone is wearing masks". Everyone is wearing masks when they're sick, not every day.

<comment><USER4> I live in Tokyo. In normal times, people wear masks when they are sick, as you say. It's good manners, consideration toward others.

But now, and since COVID-19 became a thing (February here), "everyone is wearing masks" even when they themselves are not feeling sick.

I sometimes count them when I go out and it is about 95% of people in the streets and 100% of all the shop employees I interact with.

<comment><USER23> That makes sense, thanks for the update. Where I live, it would have been extremely weird to wear a mask outside, but now all the employees wear masks everywhere. Some of them slack off sometimes and lower them to their neck, but that's about it. Amazing how cultural norms can change in a few days.

</comment></comment></comment></comment></comment><comment><USER24> "... with deaths well below 1,000, by far the fewest among the Group of Seven developed nations.... experts praise the role of Japan's contact tracers, which swung into action after the first infections were found in January. The fast response was enabled by one of Japan's inbuilt advantages -- its public health centers, which in 2018 employed more than half of 50,000 public health nurses who are experienced in infection tracing.... 'It's very analog -- it's not an app-based system like Singapore...' "

Experienced people - not tech - working for a public health program. Prepared for a blitz of 'news' about how this was a failure?

</comment><comment><USER25> So in short no one knows why it didn't hit Japan harder, but they suspect Cultural factors (mask wearing, speaking distance, etc.), along with potentially genetic factors (fewer comorbities, possibly a different strain of the virus).

The possibility of a distinctly less virulent or less severe strain of the virus seems very interesting to me. It would contribute to the story of how so many Asian countries contained the disease so successfully while Europe struggled. It would also fit the much less severe spread in the US west coast (introduced via Asia) versus the northeast (introduced via Europe).

<comment><USER26> Japan is certainly exposed to all strains because of air travel in the first couple of months. So if there is a less virulent strain it would lose to the more virulent strains out there.

Europe as a whole didn't struggle. Just look at eastern Europe or Greece or Portugal. Only parts of Europe struggled, and specifically those parts that reacted in the worst possible way, by e.g. putting sick people in nursing homes. In the US it's the same story. Most states are doing fine, and a few states royally f'd up.

<comment><USER27> Virulence describes a pathogens severity or infectiousness.

It is possible that a more infectious and less severe strain of the coronavirus could explain different outcomes in the east and west. There are a number of different strains out there.

Studies involving gene sequencing to identify strains and outcomes across different populations would be necessary to prove this one way or the other.

It could be that a solution to this would be to vaccinate people with the mild strain (as advocated by some learned people).

<comment><USER26> It's not inconceivable, but it would be a very convenient coincidence. I take it this less harmful strain also got to Greece, Belarus, Morocco, Bolivia, and Florida?

Outperformance in Asia is much better explained by partial immunity created by prior exposure to SARS/MERS. But even that doesn't explain why regions all over the world are hardly affected by covid19, including those that didn't have prior SARS/MERS exposure.

Data strongly suggests that this coronavirus is seasonal just like other coronaviruses and not especially deadly so Controlled Voluntary Infection shouldn't even be necessary (but it would work).

</comment></comment></comment></comment><comment><USER28> How can you do near zero testing then declare the curve has been flatted? You can claim anything if proof isn't required.

<comment><USER26> Either the bodies pile up or they don't. No bodies no crisis.

</comment></comment><comment><USER29> What happened to that guy who posted a few weeks ago with warnings about Japan that had tweeted hashes of his text files?

<comment><USER23> patio11?

</comment></comment><comment><USER30> [https://archive.md/uyP7B](https://archive.md/uyP7B)

</comment><comment><USER31> Anyone know why this is flagged?

<comment><USER32> The number of top comments suggesting that it's not accurately reporting the situation on the ground seem like the likely reason.

</comment></comment><comment><USER33> Unless Japan is willing to close its borders for a long time, this is a pitstop and likely mismanagement

</comment><comment><USER34> Japan barely did any testing at all, the virus is bound to have spread much further than numbers would lead to believe.

The difference is probably due to cases being mild or asymptomatic. Even older people are generally healthy, there are very few obese people in Japan and Vitamin D deficiency is relatively rare.

</comment><comment><USER35> > _No restrictions were placed on residents' movements, and businesses from > restaurants to hairdressers stayed open._

I think most of us know at this point these measures (along with laughable things like wrapping up park benches and closing access to beaches) was never going to have any material effect on the spread of the virus, but was done anyway as a way for politicians to say "look we're doing something!"

How they kept their notoriously close quarter trains from being vectors is a good question!

<comment><USER36> > I think most of us know at this point these measures (along with laughable > things like wrapping up park benches and closing access to beaches) was > never going to have any material effect on the spread of the virus, but was > done anyway as a way for politicians to say "look we're doing something!"

Wait, are you say restricting movement and closing private spaces do not affect the spread of the virus (not just as a matter of study, but obviously)? This seems to contradict the experience in much of the US (indeed of the world—but I follow US numbers more closely, since that's where I am), where the implementation of exactly these measures reduced its spread, and where numbers seem to be starting to rise again as restrictions are eased.

<comment><USER26> How would you know closing park benches or beaches works? Studies clearly show that covid19 is primarily transmitted in enclosed spaces with poor air circulation. This is also common sense, because if the virus was so contagious that it would spread on park benches or beaches then the virus would spread like wildfire in grocery stores. But we know it doesn't because people still go to grocery stores without wearing masks or taking any other precautions and cases are dropping rapidly.

<comment><USER36> > How would you know closing park benches or beaches works?

I was responding to what I took to be your full claim, which seemed to cover restricting movement as well as these two measures. (That's why my first question was whether I was understanding the full claim correctly.) I agree that closing or marking off park benches probably doesn't have much effect, but I don't know; but I think restricting movement and closing public spaces where people stay relatively still for an extended time (as opposed to, for example, trails on which people walk or run) do have an effect.

> But we know it doesn't because people still go to grocery stores without > wearing masks or taking any other precautions and cases are dropping > rapidly.

Not in the non-New York US! I admitted up front, and hasten to say again, that I am speaking from a US-centric perspective.

<comment><USER37> The USA strategy unfortunately is the re-election of the current administration, a strategy that will never have widespread support so any tactics you implement will not have widespread adoption without heavy-handed enforcement.

The countries that are dealing with the virus the best, were able to present a strategy to their population which allowed groups to create their own tactics to complement the overarching strategy.</comment></comment></comment></comment></comment>


Facebook throws out the news Paper - <AUTHOR> https://techcrunch.com/2016/06/30/recycled/ <comment><USER2> Any product/feature developed by Facebook which will give them full control should not be used by publishers or content creators.One fine day they change the algorithm or a policy and your are your own. E.g Zynga story or the Indian media sites losing millions of page views overnight . it would be interesting if the successor 'Instant articles' is used heavily.I follow a lot of news publishers on FB , In my news feed I haven't seen much of instant articles .</comment>


Ask HN: How do you browse Twitter? - <AUTHOR> I never fully understood how to use Twitter, but I have been trying to use it a bit more lately... But the whole experience is confusing.
How I do it:
I search for hashtag, then I am presented with top tweets, which are mostly tweets by established companies/pages. But I don't really want to see those so I head to Live section, because I want to see tweets by actual People. In Live section I usually have to mute some bots to get to actual content. (And Mute doesn't really work as it should unfortunately)
I do not use twitter to keep in touch with real-life acquaintances, because I cannot filter my feed easily. Yeah I know I can use lists, but I don't really want to go over all the people I follow and put them into a designated list... (I learned about lists way too late to use it effectively in my opinion.) Maybe Twitter needs some AI to curate lists for you?
I want to understand how you people use Twitter and how you benefit from it. <comment><USER2> _If you don 't like lists, then put in the necessary hard work to curate them, and you only need to do this once to enjoy Twitter_

There are so many ways to do it, and there is no 'one way' to browse Twitter, apart from deliberately being serendipitous.

Here's some lists I made:

[https://twitter.com/enginnr/lists/true- hackers](https://twitter.com/enginnr/lists/true-hackers)

[https://twitter.com/enginnr/lists/twitter- dna](https://twitter.com/enginnr/lists/twitter-dna)

[https://twitter.com/enginnr/lists/diamonds-in-the- rough](https://twitter.com/enginnr/lists/diamonds-in-the-rough)

[https://twitter.com/enginnr/lists/availability](https://twitter.com/enginnr/lists/availability)

</comment><comment><USER3> Twitter baffles me too, it primarily appears to me as a marketing channel. I prefer FB (personal) and LNKD (professional) over TWTR and G+.

Majority of tweeters I follow seem to share links only. I figure 140 character limit is not conducive to having meaningful conversations. Twitter app and site is not suitable for reviewing links.

Recently, I discovered shared links in Safari browser that seem to work better in tweet reading as it shows the pages linked in tweets too. I just quickly browse through the tweets in Safari shared links sidebar and read the linked articles that seem interesting.

</comment><comment><USER4> The Twitter site itself can be somewhat non-ideal for heavy use. The big fonts, lots of whitespace and non-chronological ordering make reading everything a chore.

You can use TweetDeck, which uses the Twitter login so you don't need another account. It's slightly better, but I still miss things like filtering.

Ideally I would like to use the API for a self-made solution, but the API troubles of the past make that tricky. You can use RSS feeds though and pipe that in some RSS reader or something else if you like that.

<comment><AUTHOR> I didn't know about TweetDeck at all. It looks a lot more useful than original Twitter. Thanks!

</comment></comment><comment><USER5> Just follow professional players from your domain and interact with them professionally, retwitting / endorsing their most relevant tweets for your own narrative. Sometimes, tweet something yourself in the same mood. Don't follow more than 50-60 profiles and act only at the busiest time of your network's Twitter day, say 4-5pm. Use it once or twice a day more to scroll the tweets from your network, say late in the morning and before shutting your connection down.

</comment><comment><USER6> I follow about 200 people, across a few different interests (mostly real friends, developers, basketball/football/hockey writers and music/tv/culture critics).

A few times per day (using an Android client), I skim through my feed rather quickly, stopping to read a few interesting tweets/conversations. Sometimes I reply to messages directed at me. Sometimes I reply to others. Often, I retweet things I find interesting and/or add a link to Pocket to read later.

</comment><comment><USER7> I don't. Twitter is crap

</comment><comment><USER8> I pretty much follow news sites and comedians. I ignore the news links mostly and laugh at some (but not all) of the comedians' jokes. I am generally on for less than 45 seconds.

</comment><comment><USER9> I'm using [http://svven.com](http://svven.com)

It discovers the people that tweet same links as I do, and gives me what else they tweet.

Disclaimer: I built it.

</comment><comment><USER10> my problem is slightly different. I would like to connect with potential users of my food site. I constantly have people following me, but when I try to private message them, they never respond. It makes me think they are bots of some sort.</comment>


Sleep deprivation is not a badge of honor - <AUTHOR> http://37signals.com/svn/posts/1006-sleep-deprivation-is-not-a-badge-of-honor

<comment><USER2> Unless you're a hockey player.</comment>


New Heroku.com site. - <AUTHOR> https://www.heroku.com/

<comment><USER2> Why would they change their design from "we have an identity" to "this is a bootstrap theme?"

</comment><comment><USER3> Good job Heroku, you now look exactly like every other shiny new flat bootstrapped web 3.0 app out there.</comment>


Apple ][ Watch - <AUTHOR> http://www.instructables.com/id/Apple-II-Watch/ <comment><USER2> From the comments:

>This is incredible and has great significance to the maker community. I would buy this over the Apple watch and would wear it too! It would go well with my nixie watch.

-stevewoz

<comment><USER3> It's not entirely clear to me whether the poster of that comment is in fact the real Steve Woz (it seems that that's his only post on the site; there's not a lot to go off of to distinguish it between a parody account and the actual guy). I sure hope it is though!

<comment><USER4> Woz linked to this instructables page on his verified Facebook account the same day as that comment. [https://www.facebook.com/thinkbig/posts/989165078413](https://www.facebook.com/thinkbig/posts/989165078413)

<comment><USER5> It looks like someone else posted this to the FB account, not the other way around.

<comment><USER6> No, Woz commented on that post with the Instructables link.

</comment></comment></comment></comment></comment><comment><USER7> I don't think I'll ever buy the actual Apple Watch, at least this generation and the next. But I'd much less reluctantly plop down $300 for this, not because of its functionality, but just for being a style accessory (isn't that the main point of watches these days) and a clever one at that. I wonder if Woz has seen this? He'd probably buy one and then try to get Integer BASIC working on it.

<comment><USER8> Look at the first comment!

<comment><USER7> LOL. Damn, I've been so trained to not read the comments on articles that I didn't even bother checking. Of course Woz chimed in, and did so in his typical low key way.

Coincidentally, yesterday I saw that he chimed in on an HN thread a year ago: [https://news.ycombinator.com/threads?id=stevewoz](https://news.ycombinator.com/threads?id=stevewoz)

Would love to see him pop in on any one of the retro computing discussions that make the front page.

<comment><USER9> Long time Instructable user. Fwiw, The comments section on Instructables is quite healthy/proactive/helpful. The community does a good job at policing, similar to HN.

</comment></comment></comment></comment><comment><USER10> At least it's not another silly Kickstarter campaign...

> 800 mAh LiPo battery (gives about a 3 hour lifetime)

Bit of a problem for a watch though.

<comment><USER11> They should make it into a pipboy then :)

<comment><USER12> [http://hackaday.com/?s=pipboy](http://hackaday.com/?s=pipboy)

You're welcome.

</comment></comment></comment><comment><USER13> This is amazing and innovative. The retro look makes it so cool that I would buy it rather than going for a real smartwatch.

The best part is, with 3d printed body, one can even make it look like a steampunk watch or say a pip-boy.

</comment><comment><USER14> The interesting thing is, imho, that the capabilities of our old microcomputers are probably exactly what a modern day watch can handle :)

<comment><USER15> From some quick searching, the CPU inside an Apple Watch is somewhere in the ballpark of the first iPad and includes 512MB of RAM.

<comment><USER16> More than enough to emulate an old computer at full speed.

<comment><USER15> Probably several old computers.

</comment></comment></comment></comment><comment><USER17> Come on guys, don't be so mean! It is just something for fun! I may spend money on this but not on the actual Apple watch... At least I can have fun with this toy.

</comment><comment><USER18> My first true love was an Apple IIc. I want this.

</comment><comment><USER19> It's not a 6502, not even an emulation.

It's a parody.

</comment><comment><USER20> This is really cool!</comment>


Partner of NSA leaks journalist held for 9 hours - <AUTHOR> http://www.foxnews.com/world/2013/08/18/partner-nsa-leaks-journalist-held-for-hours/

<comment><USER2> Previous discussion:

[https://www.hnsearch.com/search#request/submissions&q=partne...](https://www.hnsearch.com/search#request/submissions&q=partner&start=0)</comment>


The growing threat to Mark Zuckerberg's power - <AUTHOR> https://www.bbc.com/news/technology-48131048 <comment><USER2> Facebook is nothing without its users. If it starts to go down the aggressive route of ad promotion, even more people will leave.

I haven't clicked an ad in maybe 10 years and don't plan to either. The only ads I do click are on pages where I find the content extremely useful. Facebook is not one of those places.

<comment><USER3> I don't know anyone that clicks on ads. But apparently they're still valuable somehow. It's a mystery to me, but I guess even without clicks the chance to pollute someone's mind with an ad in a website is still valuable to an advertiser in the same way that it is on a freeway billboard.

<comment><USER4> Sometimes I click lots of ads deliberately to mess up the malgorithm, especially I click ads that are of no interest to me...What I never do is buy anything on the click through.

<comment><USER5> +1 for teaching me the neologism 'malgorithm'

<comment><USER4> Thanks to 'Private Eye' magazine</comment></comment></comment></comment></comment>


Eulerian Video Magnification - <AUTHOR> https://people.csail.mit.edu/mrub/evm/ <comment><USER2> So I've actually tried to implement Eulerian video magnification myself, albeit using Python, because I believe when I first looked into this, ~5 year ago, the code was MatLab only.

I was really excited about it, because, as a cardiologist, I immediately thought we could use this to identify irregular heart beats in the patient waiting room, for example. This was pre Apple watch etc. I was thinking people could briefly sit in the chair in front of the camera if they are willing to be recorded, as a quick screening whilst they wait for the doc.

Unfortunately, I found it incredibly difficult to reproduce their results, even using similar data. I remember videoing my foot as I have a relatively prominent posterior tibial pulse, which in good light I can actually make out visually (but not in the video I took, as intended). The Eulerian magnification didn't seem to do anything.

Has anyone else had better luck? I did wonder if maybe I had to use specific video capture equipment, certain frame rates or filters, but if so that wasn't clear from the documentation?

It's been 8 years since this paper came out, and yet I still haven't seen it being used in the 'real world', so I am slightly suspicious that I am not alone in my experiences.

<comment><USER3> A friend reimplementated it in python and it worked pretty well for analyzing cardiac liver movements[1]!

I don't think he is willing to share the code, but my guess is that a python implementation should work just fine, with very nice results :) (I saw the results applied in his research on videos with impressive results). It took him something like several months to have a code without major bugs.

[1] Hahn, S., Absil, J., Debeir, O., & Metens, T. (2019). Assessment of cardiac‐driven liver movements with filtered harmonic phase image representation, optical flow quantification, and motion amplification. Magnetic resonance in medicine, 81(4), 2788-2798.

<comment><USER4> Doesn't want to share the code because it works or because it doesn't work? Disgrace to science.

<comment><USER3> You are free to contact him! I'm not sure he is not willing to share.

Sharing code to the public in research depends on several factors, it can get open sourced when the thesis is done, it may depends on who is paying the research (eg: some industrial PhD are not public), long term plan exist to publish the code but there are only 24h a day and a whole lot of work to do, the author/uni may want to make a business after the thesis, and a lot of other parametres. It gets even worse when the code is used in medical applications as a validation process with all the relevant authorities has to be done. This can take a lot of time and freeze the code in the waiting for a certification. Also sharing code between researchers is very usual, it doesn't mean the code has to go public. In this case I think it is part because the original matlab code is patented, research is ongoing and as it is research code it is not necessarily public ready.

It doesn't mean he will never release it.

If you desperately need it, the matlab code is available, and has the same functionality, you are free to adapt it or use it directly (for research purposes).

I must say I don't like that the original code is patented, but I see hundreds of reasons why the authors patented it even if I don't particularly agree :)

</comment></comment></comment></comment><comment><USER5> For the unfamiliar, 'Eulerian' and 'Lagrangian' are basically just names for two different frames of reference.

Eulerian sampling is like dotting the countryside with weather stations. Your measurement data shows the weather at each of those fixed points over time and from that you can understand what was happening.

Lagrangian sampling is like sending up weather balloons. Your measurement data shows the weather around the balloons as they float along with the wind. That will give you all the same information, but from a different perspective.

The Eulerian perspective for weather makes it easier to understand what's happening at a specific location, but harder to understand what's happening to a specific particle of air. The Lagrangian perspective is the opposite.

There is an explanation of this in the paper, but IMO, it's a little more difficult to follow than the classic weather analogy. Just wanted to demystify the name a bit.

<comment><USER6> Thanks, this is nice. I presume this comes from fluids? I found this wiki link: [https://en.wikipedia.org/wiki/Lagrangian_and_Eulerian_specif...](https://en.wikipedia.org/wiki/Lagrangian_and_Eulerian_specification_of_the_flow_field).

Is this it?

<comment><USER5> Yes and yes.

</comment></comment></comment><comment><USER7> For those interested in the pulse rate extraction, there is actually a branch of biomedical engineering/computer science called "remote photoplethysmography" (rPPG).

I worked on it a bit at some point, it does work pretty well assuming you don't move that much and the light isn't too bad. As you can imagine, it's more difficult to estimate on non-white faces, particularly very dark skin tones. All the algorithms (at least until 2016) differ in the way of combining the RGB signals into a pulse signal by making different assumptions.

If you are interested more, Philips in the Netherlands are particularly active in this research domain, one of the main application being non-contact pulse estimation in hospitals for example.

</comment><comment><USER8> Related: "Learning-based Video Motion Magnification" in PyTorch. ([https://people.csail.mit.edu/tiam/deepmag/](https://people.csail.mit.edu/tiam/deepmag/))

Motion magnification" means you pick up and amplify small motions so they're easier to see. It's like a microscope for motion.

Example videos reproducing these results:

[https://twitter.com/cgst/status/1210691577078636544](https://twitter.com/cgst/status/1210691577078636544)

<comment><USER9> > It's like a microscope for motion.

Temposcope

</comment></comment><comment><USER10> William Freeman's group does lots of cool things in computational imaging and sensing, as well as ML. Fun fact: his group contributed to the formation of the first black hole image. Dr. Katie Bouman was his PhD student.

The whole field of remote photoplethysmography (rPPG) is quite interesting. I have implemented a couple algorithms, but they are quite "brittle" if you will, and only work well with certain videos. Many recent papers have introduced deep learning techniques. Hopefully these techniques are more robust to movement, skin color, lighting, and other natural conditions (unlike the usual computer vision/signal processing algorithms previously used).

</comment><comment><AUTHOR> Someone implemented this in JavaScript to work with your webcam

[https://github.com/antimatter15/evm](https://github.com/antimatter15/evm)

Demo: [https://raw.githack.com/antimatter15/evm/master/color2.html](https://raw.githack.com/antimatter15/evm/master/color2.html)

</comment><comment><USER11> I found this other video on the topic that I wanted to share. [https://www.youtube.com/watch?v=2XBQ_1t8SiQ](https://www.youtube.com/watch?v=2XBQ_1t8SiQ)

and Steve Mould's layman's video [https://youtu.be/rEoc0YoALt0](https://youtu.be/rEoc0YoALt0)

</comment><comment><USER12> This is from 2012.

<comment><USER13> Discussed at the time: [https://news.ycombinator.com/item?id=4062216](https://news.ycombinator.com/item?id=4062216)

</comment></comment><comment><USER14> I'd read that a blow to the chest during a specific phase of the heart waveform can stop the heart. In theory, this video processing algorithm, coupled to a computer fired beanbag type firearm could result in heart stoppage that would look like a heart attack.

</comment><comment> tim-fan If you'd like an easy way to try this sort of thing on your own videos, they have a demo web interface here: [https://lambda.qrilab.com/site/](https://lambda.qrilab.com/site/)

I've tried it on a couple videos with fairly interesting results

</comment><comment><USER15> Are there simpler ways of magnifying video? For example, converting to HSV and amplifying the Hue scale inter-frame differences for example?

Sorry if that seem a very simplistic approach, but curious what other techniques have been tried outside of Eulerian/Lagrangian magnification?

</comment><comment><USER16> I could not watch the video but found a better detailed explaination on youtube: [https://www.youtube.com/watch?v=DgK1Zl9asIQ](https://www.youtube.com/watch?v=DgK1Zl9asIQ)

</comment><comment><USER17> I'm shocked this hasn't surfaced as a lie detector app on the iphone. I get that it doesn't work very well, but it seems like it would sell. Maybe offer some calibration steps.

</comment><comment><USER18> Can techniques like this one used to spot "deepfake" videos?

</comment><comment><USER19> Has anyone tried to implement this as a gstreamer plugin?

</comment><comment><USER20> Is there an implementation on github of this?

</comment><comment><USER21> Quite interesting</comment>


Turn your iPhone into a high-power digital microscope for around $10 - <AUTHOR> http://www.tuaw.com/2013/10/25/turn-your-iphone-into-a-high-power-digital-microscope-for-around/ <comment><USER2> That's a fantastic hack, definitely want to build one. Here's the actual Instructables link: [http://www.instructables.com/id/10-Smartphone-to-digital- mic...](http://www.instructables.com/id/10-Smartphone-to-digital-microscope- conversion/)

There was a recent Kickstarter selling a 15X lens recently: [http://www.kickstarter.com/projects/968523355/micro-phone- le...](http://www.kickstarter.com/projects/968523355/micro-phone-lens-cell- phone-based-microscope) but this is closer to the work Dr. Aydogan Ozcan has been doing at UCLA. They started 3D printing custom backs for dumbphones years ago. An article from 2009: [http://www.nytimes.com/2009/11/08/business/08novel.html](http://www.nytimes.com/2009/11/08/business/08novel.html)

It looks like they've moved to smartphones now: [http://dailybruin.com/2013/09/27/ucla-team-invents- microscop...](http://dailybruin.com/2013/09/27/ucla-team-invents-microscope- attachment-for-cell-phones/) and they can now resolve "a single virus" and nanoparticles down to 90-100nm: [http://newsroom.ucla.edu/portal/ucla/ucla- researchers-smartp...](http://newsroom.ucla.edu/portal/ucla/ucla-researchers- smartphone-microscope-248254.aspx)

<comment><USER3> As a pathology resident, this is the kind of thing that makes me wonder if I should be looking for a new job. But everything radiology does is digital, and they haven't run out of radiology jobs, so maybe the future's not so bad...

<comment><USER2> Wells, it seems like drastically lowering costs for tools would if anything, increase demand for pathology expertise. Also, Ozcan's work has mostly been focused on developing countries - opening up new markets if you want to look at it that way.

Medical equipment manufacturers might have more to worry about, but I'd guess the amount of regulation involved will probably buffer them long enough to adapt to any changes.

What's most fascinating to me about Ozcan's work is the amount of computational photography involved for getting usable images. A few years back it was mostly MATLAB but I imagine now you could write shaders that run right in the phone GPUs...

</comment></comment></comment><comment><USER3> Pathology resident here. I really like this hack, but a fair amount of my work is at higher magnification, and requires much better correction. However, I have been very impressed with the magnifi by arcturus labs. If you already have a scope and just want to take pictures, I highly recommend it. I can take better pictures with my iphone 5 and my magnifi than some folks seem to be able to take with their far more expensive dedicated cameras. [http://arcturuslabs.com/](http://arcturuslabs.com/)

Not a shill, just a very satisfied customer.

Also, check out [http://reddit.com/r/pathology](http://reddit.com/r/pathology) for lots of what-is-that? pics!

<comment><USER4> > I can take better pictures with my iphone 5 and my magnifi than some folks > seem to be able to take with their far more expensive dedicated cameras.

Similarly, I have a friend who just bought a high-power field scope (land->land viewing instead of land->sky) and also found an adapter for the iPhone camera. Same thing happened there. The quality of his pictures is great for what it is and it's a tiny fraction of the cost of a SLR attachment or other type of digital camera.

</comment></comment><comment><USER5> While this is a nice hack, for $64 you can get a really nice and functional kid's microscope that goes up to 400x. [http://www.amazon.com/gp/product/B000NOU54O](http://www.amazon.com/gp/product/B000NOU54O)

<comment><USER6> That's six times more expensive, not digital, and not a fun hack.

I fail to understand your point.

<comment><USER7> Do you not understand what "digital" means? The kids microscope is the lens, not the image recorder. If you set up an attachment to hold your smartphone in front of the viewpiece, then anything that your eye can see can be digitized.

</comment></comment></comment><comment><USER8> After reading this, I just glued (removable) a 90 degree led lens to my phone. Nice results so far.

Edit: Link to such a lens: [http://www.alibaba.com/product- gs/611389199/Led_Light_Lens_9...](http://www.alibaba.com/product- gs/611389199/Led_Light_Lens_90_Degree_for.html)

I am happy that I turned my phone into a macro camera for a few cents. :)

Edit2: sorry, I used a 60 degree lens, not a 90 degree one.

<comment><USER9> Alibaba link has a minimum order of 5000 FWIW (but I expect it was post simply to show the type).

<comment><USER8> Exactly. I ordered mine in a pack of ten at ebay.

[http://www.ebay.com/sch/i.html?Led+lens+60+degree&_nkw=Led+l...](http://www.ebay.com/sch/i.html?Led+lens+60+degree&_nkw=Led+lens+60+degree&_sacat=0&_from=R40)

</comment></comment></comment><comment><USER10> I've done something similar but used the lens out of an old CD drive

<comment><USER8> That should be a laser lens as well.

</comment></comment><comment><USER11> If you make one, please post your results to [http://extremecloseups.reddit.com](http://extremecloseups.reddit.com) !

</comment><comment> Link- "CELLSTAGRAM" \- Instagram for cellular structures? j/k. This is an amazing hack, I remember when we were in school, we barely had access to a microscope. It was fascinating seeing the world from that perspective and always wished we could experiment with it further. This is a great hack, especially for under- privileged schools and kids in our region of the world (Lebanon, Middle East).

</comment><comment><USER12> This is definitely going to be the next weekend project with my kids. They are so scared of spiders (daddy long legs in particular, our house has thousands of them).

Time to show the girls what they look like at 175x magnification!

<comment><USER13> Maybe start with something that they want to see close up. For example, have each one pick something rough, something smooth, something that grows, a small toy, etc.

If your kids are anything like mine, starting by forcing them to confront a fear will just make them hate the technology and they'll be less willing to participate the next time you want to do a cool project with them.

<comment><USER12> Good idea, ease into it, show them some leaves, stem cross sections, then "hey I wonder what a sugar ant looks like..." lead into the spider gently

</comment></comment></comment><comment><USER14> Would this also work for non-Apple phones? The article seems to be very specific about only mentioning iThings. Is there something about them the others don't have that is required for this?

<comment><USER15> It should work with any phone.

The iThing specificness probably comes from the dimensions of the stand you need to make to hold the phone.

Just tried holding the 15mm _eyepiece_ off my old school microscope (optical) in front of the lens on my blackberry. The Thinkpad trackpoint fills the circular image field nicely (and it shows all the crud down there, so I'm cleaning it out with a brush now). Very sensitive to having the axes coincident.

Anyone any idea about the focal length of the LED pointer lens?

</comment></comment><comment><USER16> Very nice. I wonder if a similar lens could be purchased individually so a bunch of laser pointers don't have to be sacrificed.

</comment><comment><USER17> When they zoom in using the touchscreen - isn't that the digital zoom, not optical? If so, the last x10 seems not legit.

<comment><USER18> Indeed! I was going to remark the same. Also a side effect of digital zoom is that it is not perfectly sharp. You see this already in the example pictures. After all, digital zoom is more of an effect then real zooming. For this reason I never use digital zoom on a digital camera. On my PC I have software that does a better job :)

</comment></comment><comment><USER19> Do you have to worry about the focal length of the lens when doing the build, or will the phone autofocus reasonably well?

<comment><USER20> The viewing platform height is adjustable.

</comment></comment><comment><USER21> seriously cool hack; love it. This would be great for my niece.

</comment><comment><USER22> I'm guessing this is fake. A laser pointer lens would let your iPhone see cells?

<comment><USER23> [http://hackaday.com/2011/10/19/cellphone-microscope-for- abou...](http://hackaday.com/2011/10/19/cellphone-microscope-for-about-20/)

[http://www.wired.com/wiredscience/2011/03/diy-cellphone- micr...](http://www.wired.com/wiredscience/2011/03/diy-cellphone-microscope)

> Using tape, rubber and a tiny glass ball, researchers transformed an iPhone > into a cheap, yet powerful microscope able to image tiny blood cells. > They've also added a clinical-grade cellphone spectroscope that might be > able to measure some vital signs.

> And with a few dollars and some patience, you can do the same to your own > phone. (See instructions below.)

> "It still amazes me how you can build near-research-grade instruments with > cheap consumer electronics," said physicist Sebastian Wachsmann-Hogiu of the > University of California at Davis, leader of a study March 2 in PLoS ONE. > "And with cellphones, you can record and transmit data anywhere. In rural or > remote areas, you could get a diagnosis from a professional pathologist > halfway around the world."</comment></comment>


Philippines: Maria Ressa, Rey Santos Jr convicted of cyber libel - <AUTHOR> https://www.rappler.com/nation/263790-maria-ressa-reynaldo-santos-jr-convicted-cyber-libel-case-june-15-2020 <comment><AUTHOR> Original title lacked context. The country was added to the beginning of the title.

> Manila Regional Trial Court (RTC) Branch 46 convicted Rappler CEO and > executive editor Maria Ressa and former Rappler researcher-writer Reynaldo > Santos Jr over cyber libel charges in a high-profile verdict handed down > Monday, June 15. Rappler as a company was declared to have no liability.

</comment><comment><USER2> The Philippines is one of Facebook's Internet.org countries where any link tapped on Facebook isn't charged against your phone's load/balance. (the country is largely pre-paid accounts and balances)

<comment><USER3> That's not really how it worked. You got free data _on_ facebook, but you couldn't follow the links on free data. It's why misleading headlines were causing a big misinformation problem.

</comment></comment><comment><USER4> Because of Rappler's arrogance.

[https://twitter.com/abscbnnews/status/1272120272993353728?s=...](https://twitter.com/abscbnnews/status/1272120272993353728?s=21)

<comment><USER5> I don't know anything about Keng or when he did or did not make money trafficking drugs and people. He doesn't seem to have suffered much from whatever adverse coverage he received in May 2012. [0] Still... doesn't it seem possible that the government will go for any pretext to hound the primary journalistic voice that challenges some of the more outrageous abuses in Philippines? Where else should we go to keep up with what's happening there?

[0] [https://www.rappler.com/newsbreak/iq/224092-fast-facts- wilfr...](https://www.rappler.com/newsbreak/iq/224092-fast-facts-wilfredo- keng-huang-rulun)</comment></comment>


Ask HN: Would you do a usability evaluation before user testing? - <AUTHOR> In theory, would you be willing to pay for an online service, where you could easily order a customised usability research report of your website?
You would get a brief expert usability evaluation, based on research based guidelines and international standards.
Afterwards you could do usability testing with real users and get more meaningful feedback from them, since you already fixed the obvious problems. <comment></comment>


California Deputies Shoot Man Recording Them with Phone - <AUTHOR> http://photographyisnotacrime.com/2015/09/california-deputies-shoot-man-recording-them-with-phone-after-fearing-for-their-lives/ <comment><USER2> Yeah, a cellphone being held with the lens facing a person looks just like a gun from the eyes of the person being video-recorded. This is flatly ridiculous, but probably accepted by the police supervisors and district attorney when the claim comes from the cops. If I shot someone holding a telephone, claiming that it was a gun, I'd be indicted for malicious wounding or murder along with using the firearm to commit that crime.

I wonder what it's like to be able to live life without worrying about being liable to all the laws that govern behavior of society, and what it would be like to have a bunch of buddies at work, who are responsible for enforcing these laws, but who would do whatever they had to do to defend me if a worthless civilian challenged my behavior.

<comment><USER3> A window can obscure what's on the other side. Glare, reflections, lighting conditions, trees.

And sometimes people stretch out their arms to record video, just like you'd hold a handgun.

Now mix that with a tense situation and potential for life and death and I can understand they took the shot "by accident". Mistakes happen.

<comment><USER4> A person holding a cellphone looks nothing like a person holding a gun, especially to someone trained to spot people holding guns.

<comment><USER3> They're not magically trained with super eyesight after training. They're human, just like you.

Hold your cellphone up like you're recording, in portrait. See where your fingers are? Now imagine that behind a reflective window with flashing lights and you have a split second to decide if it's a weapon. If you're wrong, you die.

Try this, sit in the driving seat of a vehicle, hold your cellphone up and ask a friend to stand 20 feet away and with the sunlight at their back, look through the front glass and see if it looks like a weapon.

<comment><USER4> So it's ok to shoot people based on guesses? Did the cops even have any reason to believe there would be another shooter?

</comment></comment></comment></comment></comment><comment><USER4> Cops should be facing significantly harsher sentencing for incidents like this than private citizens, they're trained and definitely know what they're doing.

The current policy of not prosecuting police officers for mindlessly slaughtering people is rather absurd.

</comment><comment><USER5> Wow the cops shot another innocent, unarmed civilian? Don't see that happening every day... It's just not safe to violate peoples rights anymore. Might get photographed or something. Dangerous world we live in.

</comment><comment><USER6> Why do we know the name of the victim, and not the shooters?

<comment><USER7> Likely because the victim talked to the press and volunteered his name, which the others didn't and until proven guilty will not have to.

<comment><USER6> There is no right to stay out of the news.

<comment><USER4> Sure there is. It's very easy to avoid getting on the news.

<comment><USER8> For those of us who do not have the option to get on the news: what should one do to stay off of it? Let's assume that you believe you're _about_ to be on the news for something you don't want to be.

</comment></comment></comment></comment></comment><comment><USER9> "Man shoots video; police shoot back bullets"

<comment><USER10> and police apologies later, and continue on their merry way.

</comment></comment><comment><USER11> Seems like US Police forces found a new way to prevent being recorded on duty.

</comment><comment><USER12> So there's an armed standoff next door, and this guy decided it's a good idea to open his garage door and point something at the cops from their peripheral vision? And we're supposed to feel sorry for him?

<comment><AUTHOR> Yeah, recording the police is a right that has been supported in court a million times.

The cops are also supposed to be disciplined about shooting people, but whatever, that's out the window already.

<comment><USER12> It's not the recording that's the issue ...</comment></comment></comment>


Carpooling market ? - <AUTHOR>

Hey,
I'm working since a while now with one of my talented friends on a carpooling website for both users and companies, with a lot of fancy features, Until there it was only a toy, spent some long nights to talk about it, but now the development began with already some cool stuff even if we are far from the end.
Do you think a "carpooling" market really exists ? Do you know companies that could pay for this ?
Thanks for your feedback,
it's my first post on Hacker news, hello world ! <comment><AUTHOR> A way for all the coworkers to easily find the one who can share a car, so it's economic, ecologic but also social. In big companies, I'm sure you don't even know people that work in a near office.

</comment><comment><USER2> What would this offer to companies?</comment>


White House Weighing Plans for Private Spies to Counter "Deep State" Enemies - <AUTHOR> https://theintercept.com/2017/12/04/trump-white-house-weighing-plans-for-private-spies-to-counter-deep-state-enemies/ <comment><USER2> Oh boy. After private prisons, private military contractors and private police forces, we've got yet another idea that shouldn't be left to private companies being outsourced to private companies.

</comment><comment><USER3> To the degree that "deep state" == "loyal to the Constitution more than to the President", this is A Very Bad Thing(TM).

And to what degree that is, is solely at the discretion of the President.

This isn't how you run a democracy, Mr. Trump.

<comment><USER4> If this happens the precedent will outlive Trump and his administration. His successor (regardless of party) will inherit it and as we've seen it would likely expand with time. This could be the beginning of the downfall of the Republic and the rise of something more like the Roman Imperial period with the Caesars.

</comment></comment><comment><USER5> It's appalling. At least the existing intelligence services will push back, if for no other reason than protecting their turf.

</comment><comment><USER6> Another case where I wish the Anti-Pinkerton Act were actually being followed:

[https://en.m.wikipedia.org/wiki/Anti- Pinkerton_Act](https://en.m.wikipedia.org/wiki/Anti-Pinkerton_Act)

</comment><comment><USER7> The new brownshirts?

Fortunately I doubt they will find the competence to pull it off (Oliver North? Really?). And it's not in congress's interest to fund it.

<comment><USER3> The article talked about donors. Yeah, let's have the rich and the President combine to create a private army. What could go wrong?

</comment></comment><comment><USER8> If you've studied the history of how democracies devolve into empires- Germany, Rome - this should scare the piss out of you.

</comment><comment><USER9> What could go wrong?

</comment><comment><USER10> This is a good idea, keeps pressure on the entrenched partisan bureaucracies of the IC. Does anyone really think the IC -- as it functions today -- represents the interests of the common citizen?</comment>


Google officially moves to Debian for in-house Linux desktop - <AUTHOR> http://www.zdnet.com/article/google-moves-to-debian-for-in-house-linux-desktop/ <comment><USER2> "Google wouldn't say what desktop environment gLinux will be using" \- maybe because it's not strictly enforced?</comment>


BlindType demo - <AUTHOR> http://www.youtube.com/watch?v=M9b8NlMd79w

<comment><USER2> I seem to recall the guy that demo'd various multitouch research things at TED a few years back (pre-iPhone) mentioned that this would be possible. I remember thinking it sounded like a stupid idea, but this demo looks quite good.

I can't recall if he actually had something working or if he just proposed it as an idea. I notice this is patented.</comment>


Google News stops hosting new Associated Press content - <AUTHOR> http://money.cnn.com/2010/01/11/news/companies/google_associated_press/ <comment><USER2> Sounds like neither side is really hurt by this, but one has to wonder why the AP chooses to forgo the opportunity to monetize their content via another avenue besides selling it to newspapers. It seems like they are leaving money on the table for spite.</comment>


Restoring React reducer state across browser sessions - <AUTHOR> https://www.executeprogram.com/blog/restoring-react-reducer-state-across-browser-sessions <comment><USER2> > Our actual solution is to store the state in our server-side database. This > feels wrong at first glance: we're storing a client-side React component's > state as an opaque JSON blob in our server-side database, and we're doing > that knowing that some of those JSON blobs will go out of date and be > unusable in the future. But io-ts and the type system keep us honest here! > And this is a convenience feature, so we can always change it later, even if > that means throwing away all of the saved states. (When a user finishes a > lesson, that record is stored in a separate part of the database.)

That seems very... bold. That said, I could see this being useful for more ephemeral situations where it's okay to not be entirely in sync with the server. Like the user signup example: multi-step forms, or some create-only or override-always sort of arrangement, or maybe some filters for some sorting/slicing data tables, etc.

It's then useful for not being jittery on load + not storing half-baked data just to have semi-persistence of incomplete forms. Quickly rendering existing state is always a win, without resetting it then loading the updated position.

Otherwise I could see this introducing a lot of race conditions and additional work being done post-load to clean up the data.

Since there's a relatively short line here where it just makes sense to rebuild the state, it's probably preferable to utilize this for smaller isolated parts of the site, like a single form's data, instead of the wider state. But still an interesting approach none-the-less, made easier with the reducer pattern...

<comment><USER3> We only use it for resuming partially-finished lessons, so we're using it in basically the way that you describe. Overall course progress is tracked in a totally different way.

</comment></comment><comment><USER4> Two things I find weird in this approach:

1\. Why marry the state stored in the database with any particular implementation of the front-end?

2\. If the problem is in the ever changing state schema, why not create migrations for it?

<comment><USER5> Exactly, the ideal solution is the one they dismiss first.

> Solution 1: Store the current step index

Every issue they mention can be solved by assigning each step a UUID and doing proper database migrations when deleting a step so people get reassigned to a neighboring step.

<comment><USER3> I wrote the post.

Every step has had a unique ID since day one. Database migrations would be wildly more complex than our actual solution and involve a huge increase in maintenance and (depending on what you're imagining) increase database server load by multiple orders of magnitude.

Today, we can edit lessons in completely arbitrary ways, including adding and removing steps, and the system adapts dynamically. With your proposed solution, lesson content changes that take seconds today would require writing and running an entire database migration.

Your scheme doesn't address metadata at all, but metadata is one of the biggest complications discussed in the post. If you're imagining a database schema that knows about the structure of the metadata, broken into separate tables, then your scheme would amplify a single write per step (as implemented today) into hundreds of separate writes per step (with your change). Those writes would happen for every step advancement in a lesson, so a user completing a single lesson would result in thousands or possibly tens of thousands of database writes instead of the roughly 25 writes that happen today.

But regardless of whether you're imagining the metadata in an opaque blob or separate tables, it doesn't actually solve the metadata migration problem! Imagine this situation: You have tens of thousands of half-finished lesson sessions sitting in the database. Now you add a new piece of lesson metadata to the system. What do you do with those old sessions when you run your database migration? What if the relevant metadata can't be reconstructed for those old sessions (which will be the normal case)? Do you make up a fake, incorrect value for the metadata? Do you make that metadata field nullable, forever, which over time will result in all metadata being nullable, defeating the type system guarantees? Our scheme solves all of this with a relatively simple code change, and it works automatically in all situations, and it has minimal runtime overhead or database load, and it requires no ongoing maintenance whatsoever.

The metadata is mostly used for analytics. I didn't even get into this in the post, but "throw the incomplete lessons away when the metadata structure changes" is equivalent to saying "don't fabricate analytics data that will generate incorrect analytics results, which will cause us to optimize the business incorrectly."

</comment></comment></comment><comment><USER6> We did the same at a previous company. This was Redux, so maybe a little different, but it went very smoothly.

We stored a subset of the redux store locally, and a further subset of that was sent to the server. This data is quite prone to changing, so a JSON field in the database is fine. You're not going to do any advanced querying / migrations on it.

Restoring was pretty easy:

\- Try to grab from local storage

\- Try to read from remote

\- Merge those (let local overwrite remote)

\- Pass the merged object through a migration function

\- Pass the migrated data to `createStore`

The biggest pain point was dealing with TypeScript and migrations. The app only knows if the most recent store interface, so migration functions looked a lot like "old" javascript (`if (foo && foo.bar)`, `typeof foo === 'string'`, that sort of stuff).

Easy persistence / restoring is one of the many things I like about Redux.

<comment><USER7> You can express a type as one of many interfaces, or use discriminated unions ([https://www.typescriptlang.org/docs/handbook/advanced- types....](https://www.typescriptlang.org/docs/handbook/advanced- types.html#discriminated-unions)) by using some unique version key to identify each interface. Then you'll have all the goodness of types back :)</comment></comment>


Freelancers - what is your "back office" stack/setup (ex. LLC, acct/tax, etc.)? - <AUTHOR> <comment><USER2> I have a tax person - google sheets I use for timesheets/invoicing and keeping track of the business expenses (csv bank transaction import).</comment>


Ask HN: Are There Any Bitcoin Billionaires Yet? - <AUTHOR> Just a trivia question, but are there any persons who hold US$1,000,000,000 in bitcoin yet? According to CoinDesk[0], the total value of all bitcoin has just passed $40,000,000,000. So it's certainly possible. At the current value of bitcoin (2,546.85) that's a mere  Ƀ392,641.89.<p>[0] http://www.coindesk.com/data/bitcoin-market-capitalization/ <comment><USER2> It would be psychologically very hard to do.

Most people would sell at least part of their holdings after they made $1million.

</comment><comment><USER3> Those could qualify:

      - Satoshi Nakamoto (bitcoin creator(s) ~1.5M btc = $3.5B today)
      - Roger Ver (reportedly bought >$1M of btc in ~2010)
      - Winklevii (reportedly owned ~1% of all btc in 2013 = ~$2B now)
      - Ethereum funder(s) (bought >$1M of ether at 2014 crowd-sale @ $0.25, today @ ~$200/eth)
      - Chinese btc/eth mining farm owner(s)

<comment><USER4> I don't understand why people buy into Bitcoin. If I want to be part of an economic scheme where 1% of the people hold 90% of the wealth, I already have the current global economy for that. I do have a very simplistic understanding of economics but to me Bitcoin seems like all about speculation (so those that bought into it trying to make their "tokens" have any value at the expense of late suckers).

<comment><USER5> The trading aspect is speculation. It has real value though, for example as a common black market currency.

</comment></comment></comment><comment><USER6> Satoshi Nakamoto likely. I doubt that any Bitcoin Billionaires would announce themselves, though.

</comment><comment><USER7> The Winklevoss twin brothers?

Satoshi Nakamoto doesn't exist, it is a cover up.

</comment><comment><USER8> I imagine some of the theives e.g. mtgox hackers might be.

</comment><comment><USER9> Satoshi Nakamoto</comment>


You Cannot Be Serious - <AUTHOR> http://www.ttnmediagroup.com/ This must be a scam or at least a pyramid scheme, right? <comment><AUTHOR> This must be a scam, or at least a pyramid scheme, right?

<comment><USER2> Though I'm not a huge fan of Trump, I somewhat doubt he would associate his name with a pyramid scheme. This is more likely a group which will sell you on his philosophies, get you to buy his books, sign-up for seminars, etc. Think O'Reilly, but less respectable/reputable/technical/beneficial... feel free to add your own. I suspect they are just setting up a new sales channel for some of his businesses. Probably not directed at the HN community either.</comment></comment>


Infographic: Apple's Biggest Acquisitions - <AUTHOR> https://www.cbinsights.com/research/apple-biggest-acquisitions-infographic/ <comment><USER2> Tim Cook said that Apple acquires a company "every two or three weeks".....

[https://www.theverge.com/2019/5/6/18531570/apple-company- pur...](https://www.theverge.com/2019/5/6/18531570/apple-company-purchases- startups-tim-cook-buy-rate)</comment>