Thursday, 17 December 2009

LA's big lake of colloids

The New York Times is running a piece about tap water and the regulation thereof called "That Tap Water Is Legal but May Be Unhealthy". One particular contaminant becomes dangerous on exposure to sunlight so, at a lake in Los Angeles, they've tipped 400,000 plastic balls into the lake to block out the sunlight.

Perhaps this shows I've been in stat-mech too long. All I could think about upon seeing this picture was - "cool, a massive 2D elastic disc simulation!".

It's quite interesting where the crystal structure is interrupted - each one of those interfaces costs a lot of free energy. You can also see it's not truly 2D as along certain stress lines the particles have gone up and over to reduce the energy.

I wonder if it's in equilibrium or whether it'll age with time...

This is what science can do to you :-s

Don't know what fair use would be for stealing this photo but hopefully if I link to the NYT enough they won't mind - go and click on one of their ads of something...

Wednesday, 9 December 2009

Backup news

Anyone that's been here from the start will know I have a slightly unhealthy obsession with backups.  A couple of things have changed since I last blogged about this.

Time Machine
Firstly, I now have a mac at home and I've started using Time Machine. I don't want to pat Apple on the back too much because that really gets of my nerves, but Time Machine is absolutely fantastic.

It's exactly how personal backup software should work. You buy an external hard disk, tell Time Machine to backup there, and then you're done. You never need to worry about it again. Most of the time when I need my backup it's because I've accidentally deleted something I shouldn't. Time Machine allows you to, as the name suggests, just go back in time and find it before you made the mistake. Works like a dream.

After a botched attempt to upgrade to Snow Leopard I recently had my first call to do a complete system restore. All I can say is that it seemed to work perfectly for me - it didn't even take that long.

Rsync + windows
At work we backup to an external file server. Until recently that was Linux based and so I had no trouble using Rsync. Now we've been moved to a Windows server which creates all kinds of problems. Rsync just doesn't get on with Windows. Anyway, after a bit of poking around I finally have a script that does the job. This is my basic rsync call now:

rsync -rptgoDhpP --modify-window=1 --delete --log-file=RSYNCLOG --exclude-from=./exclude /home/username/ username

I'm pretty sure most of those options could be replaced with the -a but honestly, now it's working I don't want to touch it! The key command is the modify-window. This accounts for the different way that Windows and Unix file systems time stamp modified files.

SVN - Subversion
For programming and writing papers (in LaTeX) I've started using subversion to take care of version control. I'm also using a shared repository to co-write a paper at the moment - it handles simultaneous editing quite well. There is a start up cost in getting your head around how it works, I found this page very helpful, but once you're there it works very nicely.

I mention it here because the version control works a bit like a backup. You can step back through committed versions very easily. If you use OS X then it's installed along with XCode so you probably have it. With Linux it'll be in the standard repositories.

Well that's enough backup geekery for this year. Anyone using anything that they're particularly happy with? I've kind of given up on backing up over the internet for now but would be interested if there's been any developments.