Massively parallel computing on an organic molecular layer
"Here we demonstrate an assembly of molecular switches that simultaneously interact to perform a variety of computational tasks including conventional digital logic, calculating Voronoi diagrams, and simulating natural phenomena such as heat diffusion and cancer growth. As well as representing a conceptual shift from serial-processing with static architectures, our parallel, dynamically reconfigurable approach could provide a means to solve otherwise intractable computational problems."

The researchers made their different kind of computer with DDQ, a hexagonal molecule made of nitrogen, oxygen, chlorine and carbon that self-assembles in two layers on a gold substrate. The DDQ molecule can switch among four conducting states -- 0, 1, 2 and 3 -- unlike the binary switches -- 0 and 1 -- used by digital computers. [...]

Their tiny processor can solve problems for which algorithms on computers are unknown, especially interacting many-body problems, such as predictions of natural calamities and outbreaks of disease. To illustrate this feature, they mimicked two natural phenomena in the molecular layer: heat diffusion and the evolution of cancer cells.

So, it sounds like it's a 2-bit cellular automaton where each cell is composed of only 8 molecules (wow). But they said that each cell can route to ~300 others, so it must not be laid out in a hexagonal grid. My guess is that they way they are geting it to do anything is by training a neural net until it evolves custom solutions to whatever problems they have success-conditions for. But has anyone ever gotten an artificial neural network to evolve to something actually useful in the real world, or is it all still AI boondoggle?

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Radiation vaccine!

Novel nanoparticles prevent radiation damage
Radiation therapy is used to kill cancer cells and shrink tumors. But because radiation also damages normal cells, doctors must limit the dose. Melanin, the naturally occurring pigment that gives skin and hair its color, helps shield the skin from the damaging effects of sunlight and has been shown to protect against radiation.

"We wanted to devise a way to provide protective melanin to the bone marrow," said Dr. Dadachova. "That's where blood is formed, and the bone-marrow stem cells that produce blood cells are extremely susceptible to the damaging effects of radiation."

Dr. Dadachova and her colleagues focused on packaging melanin in particles so small that they would not get trapped by the lungs, liver or spleen. They created "melanin nanoparticles" by coating tiny (20 nanometers in diameter) silica (sand) particles with several layers of melanin pigment that they synthesized in their laboratory.

Anti-cancer agent stops metastasis in its tracks

They found that macroketone targets an actin cytoskeletal protein known as fascin that is critical to cell movement. In order for a cancer cell to leave a primary tumor, fascin bundles actin filaments together like a thick finger. The front edge of this finger creeps forward and pulls along the rear of the cell. Cells crawl away in the same way that an inchworm moves.

Macroketone latches on to individual fascin, preventing the actin fibers from adhering to each other and forming the pushing leading edge, Dr. Huang says. Because individual actin fibers are too soft when they are not bundled together, the cell cannot move.

The new animal experiments detailed in the study confirmed the power of macroketone. The agent did not stop the cancer cells implanted into the animals from forming tumors or from growing, but it completely prevented tumor cells from spreading, compared with control animals, he says. Even when macroketone was given after tumors formed, most cancer spread was blocked.

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mixtape 088

Please enjoy jwz mixtape 088.

This mixtape consists of some of the bands that I enjoyed most at SXSW 2010, roughly in the order that I saw them. So it is rather long, and the flow is not particularly smooth... but hey, that's what it was like being there. Embrace chaos.

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Current Music: as noted

Codesign, part 3

I'm sure I had people telling me that all this crap was working fine for them on Xcode 3.2.3.

Well, I uninstalled 3.2.3 and re-installed Xcode 3.2.2, and that makes it sign without error.

Of course, since I made the mistake (as a part of trying to figure out what was going wrong here) of upgrading my phone to 4.0b, I can no longer test the app on my phone, because only 3.2.3 will talk to the 4.0 iPhone OS. And apparently downgrading your phone back to OS 3.1.3 is an even more convoluted and flaky process than jailbreaking it.

But, it seems to have uploaded to the store and has "changed state to In Review", so we shall see if that means it made it past the DRM filter.


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Stripmall Architecture

Hey guess what, iPhone 4.0b photo app crashes every single time I take a photo. Probably violating a clickwrap NDA by telling you this. Sent from John's still-working phone.

(Also this didn't post the first time because they changed the mail client to emit that two-decade bane of my existence, multipart/related, so I had to hack my posting script to understand that too. Fuck.)

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Application failed codesign verification, WTF part 2

Ok, I can't get even a trivial, from-scratch application to code-sign. Here's what I did:

  1. Launch XCode 3.2.3 on MacOS 10.6.3.
  2. File / New Project
    • iPhone OS Application
    • OpenGL ES Application
  3. Save As: DaliClockTest
  4. Build succeeds.
  5. Set "Active Configuration" to "Release".

  6. Add a 57x57 icon to the project ("DaliClockPhone57.png")
  7. Edit "DaliClockTest-Info.plist":
    • Set CFBundleIdentifier to org.jwz.iDaliClock
    • Set CFBundleIconFile to DaliClockPhone57.png
  8. Get Info on Target "DaliClockTest"
    • Set "Code Signing Identity / Any iPhone OS Device" to "iPhone Distribution"
      (currently matches "iPhone Distribution: Jamie Zawinski")
  9. Build. Fails the same old way:
    • Application failed codesign verification. The signature was invalid, or it was not signed with an Apple submission certificate. (-19011)

In the Organizer window, Developer Profile lists "iPhone Distribution: Jamie Zawinski", Issuer "Apple Worldwide Developer Relations", and Provisioning Profiles lists "Dali Clock Distribution" with App Identifier "". The popup menu for "Code Signing Identity" also shows "iPhone Distribution: Jamie Zawinski" as being a sub-item of "Dali Clock Distribution (for Application Identifiers org.jwz.iDaliClock)", so it does appear to be seeing all this shit.

Yes, Keychain Access has "login" as my default chain. Yes, the private keys are there:

    iPhone Distribution: Jamie Zawinski [certificate, login, valid]
        Jamie Zawinski [private key, login, RSA 2048, usage: any]
    iPhone Developer: Jamie Zawinski (Y5M82TL69N) [certificate, login, valid]
        Jamie Zawinski [private key, login, RSA 2048, usage: any]

Setting the signing identity on the project as well as the target changes nothing.

Any other ideas?


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Livejournal Deathwatch continues

If there's a better example of how doomed Livejournal is than their latest news post, it can only be... their previous news posts. What qualifies as "major notes" on LJ now? "We fixed a bug that prevented you from giving us money." "We fixed a bug that caused us to steal your Amazon-affiliate-link money." "We added a server in support of a celebrity gossip community."


Since the gossip community has featured in the last three "major notes" news posts, I assume that's the only page on the site actually generating ad revenue.

I sure am glad they are paying someone to write fanfic about their goat mascot, though.

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Application failed codesign verification, WTF

Dear Lazyweb, I'm having two problems:

  1. This first problem is minor, but makes me wonder if it's indicative of something causing the second problem. When I build my app in "Debug" mode, using "Code Signing Identity: iPhone Developer", and I do "Build and Debug", the app is installed onto my iPhone, but gdb can't connect to it:

      Loading program into debugger...
      sharedlibrary apply-load-rules all
      Program loaded.
      target remote-mobile /tmp/.XcodeGDBRemote-3210-27
      Switching to remote-macosx protocol
      mem 0x1000 0x3fffffff cache
      mem 0x40000000 0xffffffff none
      mem 0x00000000 0x0fff none
      Ignoring packet error, continuing...
      Unknown packet reply: "timeout" to environment packet.
      Unknown packet reply: "timeout" to environment packet.
      The program being debugged is not being run.
      The program being debugged is not being run.

    However, the app is installed on my phone, and when I launch it manually, it runs fine. This suggests to me that the phone is in "developer mode" and has the proper provisioning profiles installed. So why can't gdb talk to it? I've rebooted both the Mac and the phone, restarted Xcode, all the usual things that the first several dozen google hits suggest. Nothing has helped.

  2. The bigger problem is that I can't seem to make a binary that is uploadable to the store. I constantly get "Application failed codesign verification". The googles suggest that this is a very common problem, but none of the suggestions I've found have done squat. (Deleted and re-installed my certs and both my development and distribution provisioning profiles, rebooted everything, etc.) Here's how the last part of the build log goes:

      /usr/bin/codesign -f -s "iPhone Distribution: Jamie Zawinski" --resource-rules=/Users/jwz/src/xdaliclock/OSX/build/Release-iphoneos/ --entitlements /Users/jwz/src/xdaliclock/OSX/build/ /Users/jwz/src/xdaliclock/OSX/build/Release-iphoneos/

      /Users/jwz/src/xdaliclock/OSX/build/Release-iphoneos/ replacing existing signature
      Validate build/Release-iphoneos/
      setenv PRODUCT_TYPE
      /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/Validation /Users/jwz/src/xdaliclock/OSX/build/Release-iphoneos/

      warning: Application failed codesign verification. The signature was invalid, or it was not signed with an Apple submission certificate. (-19011)

    So, as you see, it is signing the app (correctly using my Distribution cert, not my Development cert) and then it immediately claims that it is signed incorrectly. But, codesign says that the signature is valid, using my cert and Apple's CA:

      codesign -dvvvv build/Release-iphoneos/

      Format=bundle with Mach-O universal (armv6 armv7)
      CodeDirectory v=20100 size=2087 flags=0x0(none) hashes=96+5 location=embedded
      Signature size=4277
      Authority=iPhone Distribution: Jamie Zawinski
      Authority=Apple Worldwide Developer Relations Certification Authority
      Authority=Apple Root CA
      Signed Time=Apr 22, 2010 11:14:02 PM
      Info.plist entries=27
      Sealed Resources rules=3 files=8
      Internal requirements count=1 size=144

    The "Application Loader" application gives the same error message and no additional clues.

    Any ideas?

    Xcode 3.2.3 on 10.6.3, but I was also having these problems with Xcode 3.2.2. My phone is running 4.0 beta now, but was also failing with 3.1.3.

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The Raven

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Junk Food Science

Lay's Changing Basic Shape of Salt Crystals for Healthier Potato Chips
The salt crystals on potato chips only dissolve about 20 percent of the way on the tongue, while the center of each tiny cube-shaped crystal remains intact until after it's swallowed. Thus, most of the salt you're eating on your chips is not contributing to the taste of the chip, but it is dissolving further down your digestive tract and causing whatever the FDA alleges that increased dietary sodium intake causes.

The redesigned salt crystal, with more surface area, should dissolve completely on the tongue, thus theoretically allowing each chip to taste just as salty with only 20 percent as much salt.

"There was an opportunity for our scientists," Pepsico's chief scientific officer Mehmood Khan said. "If we could figure out a way of getting the salt crystals to dissolve faster, then we could decrease the amount of salt we put on a snack with no compromise on taste."

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