Web Excursions 2021-04-19

🌟 [Post of The Day] The Brain ‘Rotates’ Memories to Save Them From New Sensations | Quanta Magazine

  • Our ability to make sense of our surroundings, to learn, to act and to think all depend on constant, nimble interactions between perception and memory.

    • to accomplish this, the brain has to keep the two distinct;

    • otherwise, incoming data streams could interfere with representations of previous stimuli and cause us to overwrite or misinterpret important contextual information.

    • a body of research hints that the brain does not neatly partition short-term memory function exclusively into higher cognitive areas like the prefrontal cortex.

  • The memory representations were organized in what neuroscientists describe as an “orthogonal” dimension to the sensory representations, all within the same population of neurons.

    • [similar to] running out of room while taking handwritten notes on a piece of paper.

    • When that happens, “you will rotate your piece of paper 90 degrees and start writing in the margins.”

    • sensory data was transformed into a memory through a morphing of the neuronal firing patterns.

    • [Example] when monkeys are preparing to move,

      • neural activity in their motor cortex represents the potential movement

      • but does so orthogonally to avoid interfering with signals driving actual commands to the muscles.

  • To the researchers’ surprise, this combination of stable and switching neurons was enough to rotate the sensory information and transform it into memory.

  • Implications

    • feed into an emerging trend in neuroscience: that populations of neurons, even in lower sensory regions, are engaged in richer dynamic coding than was previously thought.

    • could help reconcile two sides of an ongoing debate about whether short-term memories are maintained through constant, persistent representations or through dynamic neural codes that change over time.


iOS apps are translocated when run in macOS

  • Whenever you run an iOS/iPadOS app on an M1 Mac, it’s run in app translocation, a feature introduced in 2016 for security.

  • Prior to the appearance of M1 Macs, app translocation was an additional security measure applied to some apps which were being launched for the first time on that Mac.

    • Instead of being run from their current location, the app is copied complete into a folder deep in the bowels of the hidden /var folder, and run from there.

    • This is intended to disrupt any attempts by a malicious app to exploit relative file paths, as it breaks them.

  • The requirements for app translocation

    • The quarantine flag on the app has been set.

    • The app must be opened by LaunchServices, typically by opening it in the Finder.

    • The app must be launched from its original location, and not moved from that using the Finder.

  • Since its introduction in Sierra, app translocation has caused the occasional glitch for users

  • When you run an iOS/iPadOS app on an M1 Mac, if it has been downloaded from the App Store (currently the only supported method, as sideloading is forbidden), it doesn’t have a quarantine flag.

  • The translocation path appears similar to those used for regular macOS apps which have been translocated,

    • /var/folders/x4/[characters]/X/[UUID]/d/Wrapper/.

    • The item named with a UUID is a mounted volume, and

    • the Wrapper directory contains a copy of the app, together with two Property Lists,

      • BundleMetadata.plist and

      • iTunesMetadata.plist.

    • Of the two Property Lists, iTunesMetadata.plist is by far the more interesting,

      • as it contains extensive information from the App Store about the app, its purchase and download.

      • Included among these are values for keys such as

        • sideLoadedDeviceBasedVPP and

        • is-purchased-redownload which could be used to detect attempts at sideloading.

  • Quite why Big Sur is translocating iOS/iPadOS apps every time they’re launched isn’t clear.

    • If it was just to prevent sideloading, then it’s hard to see why this is repeated after the first full run.


<abbr>: The Abbreviation element - HTML: HyperText Markup Language

The HTML Abbreviation element (<abbr>) represents an abbreviation or acronym; the optional title attribute can provide an expansion or description for the abbreviation. If present, title must contain this full description and nothing else.

FeedBurner stirs in its slumber to announce more feature deprecations

  • Last week, Google announced that they’re making changes to FeedBurner.

  • FeedBurner is a syndication feed “optimization” and analytics service that Google acquired in 2007.

    • It can count feed subscribers,

    • track views and click-through links, a feed-to-email conversion service, WebSub/PuSH, and

    • it presents people that open your feed in a browser with a webpage preview view of the feed.

    • The service is probably best known for its “subscriber count” widgets that many bloggers proudly display on their blogs.

  • FeedBurner also announced it’ll discontinue its webpage preview of feeds.

    • These page previews are intended to help users who stumble upon a feed file get started with feeds.

  • The feed preview pages are powered by XSLT, a web-standard technology that can be used to do in-browser conversions of your newsfeeds’ XML into webpages.

  • Google also announced that it would move FeedBurner to “new infrastructure”. It’s unclear what this means exactly.

  • FeedBurner is still relevant and used by major news publishers and podcasts.

    • Publishers still route their feeds through FeedBurner to get subscriber and impression analytics.

    • FeedBurner also helps speed up feed delivery using the PubHubSubhub (PuSH) standard.

      • PuSH has been deprecated for some years in favor of WebSub.

      • FeedBurner is the web’s biggest distributor of syndication feeds — and it’s stuck on an early draft of the old PuSH standard.

  • The WebHub standard is easy to implement, but most publishers rely on either FeedBurner or Superfeedr to handle the technical details for them.


CRT Pixels (@CRTpixels) / Twitter

安妮薇时报 Anyway.News • Anyway.FM 设计杂谈: 一个有趣的 Twitter 账号 @CRTpixels,对比展示各种像素艺术在不同 CRT 显示器上的实际效果

Truxton (1989, Toaplan) - Genesis/Mega Drive

RGBPi Raw Pixels vs. Sony PVM-20L2MD RGB

Love the way these enemies are rounded off and how much better the player ship stands out over RGB. pic.twitter.com/5RcBqK2zAD

— CRT Pixels (@CRTpixels) April 18, 2021


Book: The Scout Mindset: Why Some People See Things Clearly and Others Don’t: Galef, Julia:

  • When it comes to what we believe, humans see what they want to see. In other words, we have what Julia Galef calls a 'soldier' mindset. From tribalism and wishful thinking, to rationalising in our personal lives and everything in between, we are driven to defend the ideas we most want to believe - and shoot down those we don't.

  • But if we want to get things right more often we should train ourselves to think more like a scout. Unlike the soldier, a scout's goal isn't to defend one side over the other. It's to go out, survey the territory, and come back with as accurate a map as possible. Regardless of what they hope to be the case, above all, the scout wants to know what's actually true.


Ask HN: I bought Voltaren at the chemist, now Google shows me ads for it. Why?

  • jonahbenton: two high level points

    1. Remember that when you purchase something, the data about the purchase is BOTH yours AND the entity from whom you made the purchase.

      • Most of those entities have data sharing agreements of various kinds for all sorts of legitimate business reasons

    2. It isn't google who knows about the purchase, and even the advertiser doesn't "know" you made a purchase.

      • Advertising is zillions of two sided marketplaces,

        • with an enormous ecosystem of data packagers and conveyers and linkers,

        • with lots of concern about recency and freshness of data.

      • Your purchase landed some key about you in a bucket

        • that was mixed and repackaged with many other keys that the advertiser knows as "keys recently interested in Voltaren."

          • Some of those keys are related to people who bought it, or

          • who searched for it, or

          • more indirectly who lingered while reading a page with an ad for it...

        • and in most cases are very short lived.

      • So give it a few weeks and many of those buckets of keys will have been completely remade.


Bitcoin Mining Hash Rate Drops As Blackouts Instituted In China

  • Local news outlets have tied a recent dip in the bitcoin mining hash rate to government-instituted blackouts in China.

  • Regional blackouts instituted in Northwest China may be the cause of a drop in hash rate from several China-based bitcoin mining operations

  • The blackouts were necessitated because of a “comprehensive power outage safety inspection”

    • the regions of China combined account for more than 50 percent of the overall Bitcoin mining hash rate