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scratcheee

394 karma · joined May 13, 2021

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scratcheee··on A low-cost and shielding-free ultra-low-field brain MRI scanner
Yes, but context is key.

Denoising can on average improve the result, but sometimes it will be wrong.

Spotting when it goes wrong is potentially a difficult task, but generally the difficulty scales pretty clearly with the difficulty of understanding the original image anyway. If you can't spot when a denoising filter has screwed up, chances are you wouldn't have spotted anything interesting in the original image anyway.

But once an AI is context-aware things get way more complicated - it will try very hard to produce an image that doesn't _look_ wrong. Even if it goes wrong, it can go wrong and still succeed in managing to make an image that looks correct, it just no longer matches the real brain that was scanned. Perhaps it decided a tumor was just a smudge on the lense, and invented some brain to go behind it. An operator expecting to see brain and seeing brain wont think anything of it. When the patient dies, they may look back and say "wow, that tumor didn't exist at all just 3 days before! that should be impossible!".

tldr: Having an ai that might make mistakes is one thing, having an ai that can just invent exactly the data everyone is expecting to see is dangerous.

scratcheee··on A low-cost and shielding-free ultra-low-field brain MRI scanner
Exactly my thoughts too. I'm fine with a simple noise-removal pass, but if the AI is context-aware, what's to stop it saying "hmm, this brain would look more like a normal brain if I remove these tumors". Obviously, they'll test for that, but that only handles common cases they concider, it's always going to be a risk for more unusual sceanrios, and the danger with altering the data is that anyone looking at the results wont have a way to tell how dubious that data is.

Reminds me of https://en.wikipedia.org/wiki/Xerox#Character_substitution_b... which was _so much_ worse than the equivilent OCR bug because it occured at the image level, where everyone expects errors to to produce noise, not contextly sensible and sharp _but wrong_ characters.

EDIT: based on other comments below, this is thankfully not the case, the AI just understands noise, it doesn't try to "fill in the blanks" based on how brains are supposed to look.

scratcheee··on Retrospective and technical details on the recent Firefox outage
They explained that in the retrospective.

The code _does_ work the way you describe, _except_ for the latent bug that caused the networking thread to get stuck in an infinite loop, which it was never supposed to do, even when errors occur.

It was never supposed to work that way, and the fact it did was because of a bug they'd never seen before.

So it wasn't that "oops, we shouldn't have built the system to get stuck forever when it fails" but rather "this bug triggered that bug which combined to cause a far worse result than 1 bug alone could have".

The only "lesson learnt" there is either that they need better ways to find bugs, quadruple up their thread count just so that different subsystems can't coexist on the same threads to avoid a theoretical problem that shouldn't ever happen again, or they just come up with infrastructural changes to minimise the negative results of the next "2 bugs reacted together and caught fire" scenario, which is the one they went with, and the only sane one.

scratcheee··on Risky Food-Finding Strategy Could Be a Key to Human Success
They're using efficiency in a different (and certainly confusing) sense.

Their gas guzzling car example explains their thought process: humans, whilst hunting, are running hot. They're inefficient at the task of maintaining themselves between meals.

That's made irrelevant by the fact that they're collecting more food on average, so they're actually more efficient overall, but that only becomes true once you factor in food intake.

Sort of like saying that a lorry is a less efficient way to travel than a car. True until you mention that the lorry has many tons of cargo which must make the journey with you (or in subsequent trips), _then_ the reverse holds.

scratcheee··on Scientists believed Covid leaked from Wuhan lab, but feared debate could hurt
I don't have faith in true (aka direct) democracy. It relies on the average person being well informed enough about everything involved in running the government to make good decisions. It also relies on every person in the country acting in good faith for the benefit of all, which at best you could convince _most_ people to do _most_ of the time.

I do have faith in representative democracy to do _approximately_ the right thing most of the time, or at least minimise how bad the bad results will be.

In other words, I think people are better at deciding who to trust to run the country than they are at actually running the country. Given that, it should be no surprise that I also think there will be situations where the person trusted to run the country will realise that telling the public the whole truth will be a bad idea, because they are better at interpretting that truth than the public is.

Lying to the public is not (imo) a slippery slope that inevitably makes anyone who goes down it a monster. Polititians can be something other than perfectly honest and actually satan, and in fact they must be. I think a perfectly honest polititian would be a bad thing overall, even beyond the fact that their career wouldn't last very long.

Where on that scale they should be is in the end in the hands of the public, via our democratic vote. Certainly I don't support constant lies and hiding of things the public needs to know. But that isn't what we're discussing here, we're discussing a single lie used for a good cause (though I admit it was probably not the best solution to the problem, it was at least a logical concept: convince people who need masks less to not panic buy masks, leading to more masks for people who need them more).

scratcheee··on Scientists believed Covid leaked from Wuhan lab, but feared debate could hurt
Yes, certainly would have been a better angle. I suspect bad/limited data played into that, but it does seem like a fairly obvious direction to go in nonetheless.
scratcheee··on Scientists believed Covid leaked from Wuhan lab, but feared debate could hurt
That's a fair point, although in this case drawing attention to the shortage would have made it even more newsworthy, and might have made the few greedy profiteers more fervent in their desire to buy up all stock, even as the average person reduced their buying. Appealing to morality works better when each person gets an approximately equal vote. If one arsehole can counteract the good behaviour of 10, that weakens the honest approach.

Whether it would have actually been worse or better I can't really guess, but I do see your point that it might have worked and definitely wouldn't have weakened public trust the way the dishonest approach did, so yeah, I'll concede that was probably a bad call.

scratcheee··on Scientists believed Covid leaked from Wuhan lab, but feared debate could hurt
This may be unpopular, but I'm actually fine with polititians manipulating the truth in that scenario (_if_ we accept as a starting point that the shortage of masks was already unavoidable, and the best option for public health was to convince the public to minimise purchases). Part of the job of politicians is to act as a rudder for the general public, and if tragedy of the commons applies to a scenario, a politician doing what they can to counteract that effect, even by deceipt, isn't fundamentally wrong (if it's for a genuinely good cause and the situation didn't have a less distasteful solution). If polititians need to tell us that there is no fuel shortage to avoid a rush that worsens the fuel shortage, so be it. It is (and _should_ be) assumed that polititians are manipulating the truth, the only question is whether they're doing it at a level and for a cause that are acceptable.

I am _much_ less comfortable by similar behaviour in scientists. Science is built on trust and a pursuit of truth, lying is anathema. This is true both within scientific debate, and from the outside, when scientists share their perspective it should be a counter balance to the more flexible interpretation of truth provided elsewhere.

Tldr: Polititians can and should play politics (politics _is_ mostly white lies, or just lies, depending on your cynicism level). Scientists should not, it hurts the reputation of science as a whole.

scratcheee··on Firefox 96
That would be the problem if 1. firefox only had a _literal_ handful of users (rather than 100s of millions), or 2. if any browser was _that_ good at anti-fingerprinting.

But at the moment which browser you use is nowhere near as powerful in identifying you as the rest of the huge fingerprinting surface available.

Fingerprinting currently gives pretty much everyone a unique fingerprint in almost every browser, so even if only 100 people managed to share a fingerprint, that would already be a big success. Firefoxes relatively low usage share doesn't currently add up to any real significance in the fingerprinting calculus.

scratcheee··on Firefox 96
If it's crashing your computer you can pretty squarely place the blame on the driver, not the browser.

Without bugs in the driver, even bad behaviour from the browser shouldn't bring the whole machine down.

Graphics drivers are sadly famously buggy, and occasionally the hardware is buggy too, and the driver needs to work around those bugs in the hardware, and occasionally the users hardware specifically is broken in some way, and then there's no winning.

It's probably true that Firefox has less workarounds for buggy drivers hardcoded into it than Chromium, but in the end the blame is on the driver, and if they had blacklisted your driver the likely "improvement" is you'd no longer have any hardware accelleration, which is not exactly a great result - the real fix needs to be better drivers that don't crash the system for no good reason.

scratcheee··on LibreQoS: QoS for ISPs
This has very little to do with qos tags, which frankly don't work well for this use-case, even if everyone involved suddenly decided to support them.

This is about how the router handles traffic flows when congested. The naive (and all too common) solution is to just lump all the traffic into a big buffer and push it through in fifo order.

QoS algorithms like those used here tend to handle each stream individually, giving each an appropriate buffer and bandwidth. This means "thin" streams (voip) can have very low latency even when fat streams (80 people downloading the latest computer game) are eating all the bandwidth available and begging for more. The thin stream can easily get through the link and "should" be fast and low latency and drop no packets, it barely even needs a buffer, but the fat streams certainly do need a buffer, _must_ drop packets (that's the only way they know how fat they're allowed to be), and can accept higher latencies with no negative effects.

fq-codel/cake try to handle the streams in a way that well behaving streams get a link that "feels" like everyone is behaving well, and greedy streams don't ruin that experience for everyone, only themselves.

Even greedy streams benefit, since packets can be dropped earlier by smarter qos systems (rather than waiting until they're using the whole buffer), it can work out the optimal amount of buffer given the link speed, which is often not the same as an arbitrarily picked buffer size. Too little buffer and you lose throughput, too much and every packet sits waiting in a buffer for 200ms for no good reason.

scratcheee··on Reimagining projections for the interactive maps era
I'm curious how it would work out if you updated the projection center to match the view center in zoomed out maps?

I can see a value in having a "stable" map that doesn't twist around as you move, but I think that would offer a good alternative for people trying to look at places that suffer from the traditional projection centers, and of course different trade offs make sense for different circumstance.

But perhaps constantly reprojecting is too expensive?

scratcheee··on Father-son duo helped techies ‘hack exams’, earn top scores for big payday
India is currently undergoing the inflection point of development.

There's a _lot_ of very poor people in India, vastly more so than in a "fully developed" nation.

But at the same time, India's recent economic growth is enormous, giving a far larger percentage of the population opportunities they've never had before.

But there's enormous competition for those opportunities.

So basically it's the right moment (more like "right half century") for India to have this problem, there's so much opportunity but also so much competition, that each small step forwards academically can mean a jumping a generation ahead of the curve on economic growth.

To put it another way, you can model economic development by chucking a lump of meat to a school of starving piranhas.

scratcheee··on Firefox is the alternative to a Chrome hegemony
Mozilla have been losing market share when the barrier to entry is "install this free alternative to your existing browser" the chance that they could succeed with "buy this paid alternative to your existing browser" is approaching zero.

Opera was paid at one point, they lost the competition with free alternatives.

Paid browsers are a concept that has been and gone, and if Mozilla attempted to bring the idea back, it would probably be the stupidest decision Mozilla had ever made. They have made plenty of stupid decisions, but nothing so far has utterly destroyed their market share instantly, this would.

In the end, the funding model alone doesn't define how a company acts. It matters, and is certainly a threat to Mozilla's neutrality, but Mozilla tends to hire developers who care about thier mission, they tend towards openness in their processes. Both these things protect Mozilla from becoming a Google shill despite their funding process.

If Mozilla ever backed Google on the wrong decision, I trust that many Mozilla devs would push back - either internally or by going to the press, even if it cost their jobs. Being a particularly successful open source project tends to select for a certain kind of employee.

Apple devs don't have this advantage - Apple has a culture of secrecy (for prefectly understandable buisness reasons, they don't like leaks), this means Apple's decisions are much harder to monitor, and Apple devs are much less likely to fight internal decisions that hurt the web as a whole.

That said, Apple does have its own incentives to fight Google which are also legitimate - a more independent funding model, and an intense dislike within their internal culture of relying on external vendors for their software and apis. There's a reason Apple develop their own browser, their own compiler, their own dev environment, their own everything. There's a history to that, Apple have been bitten by externally controlled systems, so they are very unlikely to jump to Chrome, probably even moreso than Mozilla.

The point is, both Mozilla and Apple have good and bad elements to their continued position providing alternative browser engines, both are strong in their own ways, and we're vastly better off with the benefits of both than with just 1 of them, either would be a major loss.

scratcheee··on Ancient secrets of computer vision
I agree it's very cool, but I have found it to be surprisingly poor in certain scenarios.

A "faint" circle will often score worse than 2 high-contrast parallel lines that happen to be the right distance apart, since the lines manage to trigger pixels along 20% of a circle's arc and their contrast massively inflates their score compared to the faint circle (higher edge pixel density).

It seems like there should be a simple way to weight the results by how dispersed within the circle's arc the pixels are, but I've never dug any further, after hitting this problem I had to move on.

scratcheee··on Endianness, a constant source of conflict for decades
>[big endian] Binary dumps look more in line with how humans with left-to-right scripts expect to read numbers.

Maybe I'm just dumb, but surely the actual language order is entirely irrelevant? If hypothetically we wrote in English right-to-left instead, then we'd write our numbers right-to-left, and our memory dumps right-to-left, so then we'd find that little-endian caused the data to start with the smallest byte first (on the right).

Mirroring the language doesn't undo a mirroring within the language, and that's what little-endian is, so a more accurate statement would be:

>Binary dumps look more in line with how humans with single-direction scripts expect to read numbers.

scratcheee··on IPv4 pricing
At the current rate (approximately linear over the last 10 years), in just 30 more years we'll have 100% adoption.

Realistically adoption will slow down if nothing changes, everyone willing to put the effort in for zero immediate reward has already done so, and some will allow their support to degrade due to low usage.

At some point I guess ipv4 availability will really start to collapse and adoption will speed up again.

Not sure which will come first to be honest, but better if adoption is relatively high when the shit evebtually hits the fan, to avoid the temptation of insane NAT solutions.

scratcheee··on Math Problems for children from 5 to 15 (2004) [pdf]
The bookworm could have moved right to left from volume 1 to volume 2. Assuming the spines are facing out, the books are right-way up, and volume 2 is on the left of volume 1, then the answer would be 44mm.
scratcheee··on Math Problems for children from 5 to 15 (2004) [pdf]
Assuming volume 1 is on the left and the books have their spine facing out.

Reasonable assumptions, but relying on implicit knowledge nonetheless.

scratcheee··on John Steinbeck’s estate urged to let the world read his shunned werewolf novel
copyright is automatic and implied, if someone somehow got a legal opportunity to see it, and managed to copy the work (or indeed if the publisher who originally refused it decided to publish it from their records), they would be breaking copyright from the original work regardless.

But once the copyright runs out then the publisher can publish it regardless, and a viewer could quietly copy it and publish it, unless someone in the estate made altered copies for anyone viewing it, then the altered copies would have fresh copyright, confusing the whole issue.

scratcheee··on Vue 3 drops IE11 support plan
Ah yes, I remember loving that feature in Netscape at the tail end, when it was just an altered clone of Firefox.

I got used to losing it eventually after switching over, but I do remember it being a painful transition for me too.

scratcheee··on Vue 3 drops IE11 support plan
There's multiple extensions that claim to provide a shortcut to the duplicate tab option, fwiw
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