X Sharing Screens

Found this in my archive, I dunno where from..

When I pop up with my laptop to discuss with a colleague, after a while I might do on their computer:

xhost +mylaptopname

and on my laptop I do:

x2x thecomputername:0 -west

Then suddenly my mouse can go over the two computers, my keyboard works on both as well, and I can even copy-paste between the two computers. It looks like the two computers got united. In a flash, newbies get a new idea of what means unix and X ;-

but I thought it was worth reposting.

Ubuntu Jaunty seems to have just updated its wireless network and broke my settings. Had to change the mode from Infrastructure to Ad-Hoc in the connection settings.

Techdirt

This is a bit of an e-vote for TechDirt. I don't agree with everything those guys say, but lately they've had several in-depth articles and they research their stuff well and are honest when they're wrong.

Techdirt.

Last Piece Puzzle

So I was away on holiday and I found a puzzle called the Last Piece Puzzle. Basically trying to arrange tetris-like pieces to fill a square with no gaps.

I wrote a program to solve it, which was going to take about thirty years to try every combination. The second attempt found all possible solutions in about 2 minutes.

The difference between the two algorithms is what gets me - it's so subtle. The first algorithm picked a piece and then tried every position on the board for that piece, then once it found a position, it moved on to the next piece. The problem here is that there were often holes left behind that no piece would fit into, so it spent a lot of time trying to solve a board that obviously couldn't be solved.

The second algorithm was only slightly different - instead of trying the pieces in order, try to fill the squares in order. This way there were almost no holes (or the holes were found without too much extra effort) and the algorithm turned out to be hugely faster.

There was a contest to solve it in lisp - the fastest solution there was 0.3 seconds. My second attempt copied the winning algorithm there.

My solution is also floating around.

In total, there are five possible solutions:

Atom printing

Just went to the sweetest talk about 0.2A (1A lateral) resolution atomic tomography. Basically kick atoms off a (needle) surface with an electrical pulse or laser and then accelerate them into a position sensing detector. The time-of-flight gives you the mass-to-charge ratio so you can tell element and isotype. As the electric field spreads out almost radially away from the needle you get a lot of magnification and can tell the originating position quite accurately.

Of course, this imaging method destroys the sample.. but wouldn't it be cool if you could do it in reverse to place individual atoms into an object? It would be difficult to say the least, but the result would be awesome. Not only that, but it could be a quite automatic process.

You could have different print heads for different elements. Perhaps even the same thing in reverse, a laser that kicks atoms off the "print head" and then the freed ion travels along the electric field line and hits the "needle". Of course, you would have to ensure that the ion got kicked off with a small velocity or you would have quite bad lateral resolution. This low velocity thing would probably result in the ion just reattaching to the material. So this is probably hard to do, because the whole point of using a needle is presumably so as to get strong electric fields (and thus high acceleration) when the ion is first ionised. Perhaps this is why this technique won't work.

But what if you had two needles? Boot the atoms off one, and attach them to the other. Ensure that only certain atoms land by having a (macro scale) aperture between them and detect when atoms land.

Jaunty

Things to fix for Ubuntu Jaunty install on an M1330 (so far):

Set Source in synaptic to whatever ISP I'm currently using (avoid quota usage)

System->Administration->Hardware Drivers, enable latest

Install packages:
texmaker texlive-math-extra
blender inkscape
idle
compiz-fusion-plugins-extra compizconfig-settings-manager

Audio (crackles instead of proper sound):
change /etc/modprobe.d/alsa.conf
add line
options snd-hda-intel model=3stack
as my laptop has three audio ports
(ref: https://help.ubuntu.com/community/SoundTroubleshooting )

CD/DVD (disks don't mount properly):
add line to /etc/fstab:
/dev/sr0 /media/cdrom0 iso9660,udf user,noauto,exec,utf8 0 0
and make sure the other lines match the order of is09660,udf.
(ref: http://osdir.com/ml/ubuntu-users/2009-05/msg00352.html)

HDD power management (hd spins up/down constantly):
add
/dev/sda {
apm = 255
}
to /etc/hdparm.conf
and change /etc/acpi/resume.d/*hdparm* and /etc/acpi/start.d/*hdparm* :
change all three-digit numbers (128, 254) to 255.
(ref http://www.gatzet.com/fixing-ubuntu-harddisk-power-management-bug.html)

Closing the lid of the laptop should make it sleep:
System->Preferences->Power Management
On AC Power, When Laptop Lid is Closed, Suspend.

Firefox extensions:
flashblock chatzilla

Configure Inkscape to use SVG properly.

3DMagix is a rebranded blender.

This post is part of a google bombing campaign, because I love Blender 3D.

3DMagix is a rip-off.