Analysing Spatiall Embedded Networks

I realized this would probably be a decent place to describe some of the work I've been doing and hopefully get some feedback. I've been working at the intersection of spatial information and network information, trying to develop ways of integrating the two types of information. This is not the "spatial networks" that are used to analyze space syntax and transportation networks. Instead, I'm interested in looking at arbitrary networks of things where some of the things are labeled with spatial location information.

So far I've analyzed drug seizure networks, shipping networks, organizational network of terrorist groups, epidemiological networks and simulated social networks. Most of this analysis has been to test new methodologies I've developed. There are two main techniques I've been working on, manipulating network scale and aggregation and visualizing spatial dependencies in network topology.

There is a fundamental discord between network and space. Space is continuous; relationships in networks are defined as between discrete entities. This means that some level of aggregation of space (implicit or explicit) us required in order to do a meaningful analysis of the network. Different levels of aggregation can lead do quite different networks. I've been working on methods of capturing the tradeoffs of aggregation versus precision.

Second, visualization of social networks has been important historically in providing the intuition for many commonly used network statistics. My hope is that the visualization of spatially embedded network data will be similarly useful. However, simple visualizations of spatially embedded networks quickly become noisy and difficult to interpret. For this reason, I'm developing techniques for visualizing higher-level network topological properties and their interaction with spatial location. I am also working to develop a statistical measure of the spatial dependencies in structural properties of a spatially embedded network.

All of these techniques and more have been implemented in the Geospatial Network Visualizer in the ORA dynamic network analysis tool.

Managing Bibtex and PDFs with JabRef!

A few days ago, I decided it was time for my assorted bibtex files to grow up and get organized. I also decided that my assorted pdfs of papers should also get centralized and organized. I had the crazy idea, that there might be a tool that could do both of these tasks in an open, portable format that I could easily transition if I grew tired of the tool. Unlike past endeavors, in this task I succeeded beyond all expectation. The JabRef reference manager is an open source reference manager that uses the standard bibtex format as a backend. Unlike other tools I tried, it works, simple and pretty feature-complete, it provides a centralized location to store references, notes/review/summaries of said references, as well as links to the actual pdfs (when you have them). JabRef will automatically generate bibtex keys for you, if you ask it, and if you save your pdfs with the respective key in its filename, JabRef can automatically find the file and associate it with the intended reference! Plus, like many of the other tools, it can automatically sync up to many of the online databases and download documents if you have access to them.

It also has extremely flexible keyword/category-based organization of references. Your categories can inherit either supercategories, subcategories, or neither.

Cisco VPN client in Ubuntu 8.10

I'm not sure what changed, but I can't seem to get the Cisco VPN client working in Ubuntu 8.10. In 8.04 I'd gotten things working by following instructions like these. Once again, the good folks at tuxx-home.at had a few solutions, but I couldn't get them to work. Either seg faults when it ran or compiler errors and it wouldn't. Anyway, I'd been leery, of trying vpnc since my .pcf files for the SCS at Carnegie Mellon didn't quite look like any of the examples. However, when I eventually tried this decoder with my encoded group password, everything worked out! Now I just use the NetworkManager applet to manage my vpn and it all (mostly) works.

FGLRX Sadness

I was reminded once again of why other people give up on linux when I walked over to my new desktop only to find that the 3d graphics driver, fglrx, had decided not to work. I spent several hours over the next few days trying to track down the issue, uninstalling, reinstalling, reverting to older versions of the driver, xserver, the linux kernel, all to no avail. Eventually, I gave up and am now using the 2d open source drivers. The fglrx driver had even stopped working adequately for simple window management things.