Arch Linux, systemd, and RAID.

May 13, 2016

Long, long time readers of my blog might remember Leandra, the server that I've had running in my lab in one configuration or another since high school (10th grade, in point of fact). She's been through many different incarnations and has run pretty much every x86 CPU ever made since the 80386. She's also run most of the major distributions of Linux out there, starting with Slackware and most recently running Arch Linux (all of the packages of Gentoo with none of the spending hours compiling everything under the sun or fighting with USE flags). It's also possible to get a full Linux install going with only the packages you need in a relatively small amount of disk space; my multimedia machine, for example, is only 2.7 gigabytes in size and Leandra as she stands right now has a relatively svelte 1.1 gigabytes of systemware. However, Arch Linux was an early adopter of something called systemd, which aims to be a complete replacement of the traditional UNIX-like init system that tries to manage dependencies of services, parallelize startup and shutdown of system features, automatically start and stop stuff, replace text-based system logs with a binary database, and all sorts of bleeding edge stuff like that.

Some people love systemd. Some people hate systemd. Personally, I think it is what my besainted grandmother would say, enough to piss off the Pope. That's not really what I'm writing about, though. What I'm writing about is a problem I ran into getting Leandra back up and running after building a fairly sizeable RAID array with logical volumes built on top of it.

Can't come up for air just yet.

May 04, 2016

Hacking code and writing policy. I'll be able to come up for air soon.

Also, claims that they're migrating to their old URL and that everything is fine. Only everything's not fine, nobody's links load, their blog is now gone, and they're not responding to anybody trying to get in touch with them. I'm glad I was able to download my data (including all the stuff I want to write about when I get a chance) before their site started acting screwy again. I guess I'm going to need to set up my own online link manager...

Hacking DNA. No, really.

Apr 02, 2016

Last year a new genetic engineering technology called CRISPR - Clustered Regularly Interspaced Short Palindromic Repeats - showed up on my radar at a local conference. Long story short, CRISPR is a highly precise technique for editing DNA in situ which follows from the discovery of short sequences of DNA which allow for precise location of individual genes. It's a fascinating technology; there are even tutorials (archived copy, just in case) online for developing your own guide RNA to implement CRISPR/Cas9. What you might not have known is that CRISPR/Cas9 is being actively studied as a theraputic technique in humans due to the amazing amount of success it's shown in modifying the genomes of other forms of life. At Temple University in Philadelphia, Pennsylvania earlier this year molecular biologists successfully used the technique to hack the DNA of cultured human T-cells in vitro that were infected with HIV and delete the HIV DNA entirely. Moreover, when re-exposed to HIV the hacked T-cells were observed to show immunity to the virus. Further observing the cells after they'd been modified showed that no adverse effects were introduced - the cells were healthy, happy, and just as effective post-CRISPR/Cas9 modification as pre-infection with HIV. The research team's peer-reviewed findings were published in the journal Nature in February of 2016, and the paper went open access online in March of this year.

3D printing of nanomaterials and implanted prosthetic limbs.

Apr 02, 2016

Long-time readers of my site no doubt know of my fascination with the field of 3D printing and tracking the advances that are made almost weekly to this technology. From simple plastic tchotchkes to replacement parts to materials that few ever dreamed would be used, 3D fabbers are fast becoming an integral part of manufacturing at all levels of complexity. A few months ago researchers at Lawrence Livermore National Laboratory published the results for a revolutionary 3D printer called the Optomec Aerosol Jet 500, a fabber which uses a range of nanomaterials as its feedstock. To cut to the chase they've been using it to construct electronic components and integrated circuits at the molecular level, laying down conductive pathways in three dimensions, constructing semiconductor units material by material, and linking everything together into working circuitry in situ. Current semiconductor prototyping fabs are huge, on the order of thousands of square feet in size but the Optomec is just slightly over 250 square feet in size, well within the working space of your average science lab (and doesn't use any of the incredibly dangerous chemicals ordinarily involved in semiconductor manufacture). The new generation fabber prints at a resolution of 10 microns, which is about the size of a large grain of pollen or silt but far to small for the human eye to discern unaided. I don't know when this technology will leave the lab but you can bet that the semiconductor giants are going to be keeping a close eye indeed on them, if only because eliminating many of the chemicals they use would raise their bottom line significantly (by not needing to worry about licensing and disposal costs).