Friday, March 16, 2012

Tidbits

Some interesting and thought-provoking things have come up in the last week or so. For instance, here is an article from the IEEE that discusses the decline in science and engineering jobs in the US. Figure 2 is particularly thought-provoking, showing that the number of US undergrad STEM degrees is very strongly correlated with the number of non-medical US federal research dollars spent, from 1955-2000. My personal take is, if you really want Americans to become scientists, engineers, and more broadly supportive of technical education, you need to create a culture where those professions are (more) respected and valued, not viewed as nerdy, geeky, asocial, elitist, or otherwise unacceptable.

On this same theme, there was this op-ed in the New York Times about why so few American political figures are scientists. Accurate (in my opinion) and depressing. I'm not saying we should live in a society run by technocrats, but surely we can be better than this. As a culture, do we really need more lawyers and undergrad "business" majors?

On a more technical note, the ICARUS collaboration, another group in Gran Sasso in Italy working with neutrinos produced by CERN, has announced (paper here) that their measurements show neutrinos traveling at a speed consistent w/ c. Not surprising, and only truly independent measurements can really pin down the issues w/ the OPERA work.

Here is a beautiful new paper by the Manoharan group at Stanford. By arranging spatially ordered arrays of CO molecules on a copper surface, they can manipulate surface states in a way that produces dispersion relations (the relationship between energy and momentum for electrons) with the same kinds of features seen in graphene. While I haven't had a chance to read this in detail yet, it is very slick, and makes explicit the connection between real-space distortions of the graphene structure and how these are mathematically equivalent to electric and magnetic fields for the charge carriers confined to that 2d environment. It's also a great demonstration of how the motion of charge carriers in a condensed matter environment depends on the potential energy's distribution as a function of position, rather than the details. Here, the electrons are not carbon p electrons feeling the "chickenwire" potential energy of the carbon atom lattice in graphene. Rather, the electrons are those that live in the copper surface state, and they feel a designer "chickenwire" potential energy due to the arrangement of CO molecules on the copper surface. However, the net effect is the same. Very pretty. (Still makes me wonder a bit about the details, though.... At the end of the day, electrons have to scatter out of that surface state and into the bulk for the STM measurement to work, and yet that process has to be sufficiently weak that it doesn't screw up the surface state much. Very fortunate that the numbers happen to work!)

Finally, here is a cool, fun project, using nanofab tools to make art (too small to see with the unaided eye). Sameer Walavalkar did his PhD with the well known nano group of Axel Sherer at CalTech. This kind of creative outlet is another way to do outreach, and it's a heck of a lot cooler than many other approaches.

6 comments:

Narasimhan said...

Dear Doug,

In fact yesterday's (3/16) Science Friday specifically discussed this issue.

Here is the link.

Science Friday

With Regards
Narasimhan

Anonymous said...

With regards to the last link: the nano art is indeed cool. But something doesn't sit well with me. Unless this fellow has his own FIB, it strikes me as misuse of a University resources. If he's collecting money that will be used to compensate CalTech for use of the FIB, then I guess I don't mind so much. But it seems like he's been doing a lot of this...

This comes from a grad student who had to fight for access to cleanroom resources. Also, the acquisition of many of these tools is funded with federal grant money.

Doug Natelson said...

Anon., I had the same concerns, and checked with him before I posted this. Yes, he has the university's permission, and yes, he has to pay for access (which is one reason his pieces are priced at that level).

Igor Fridman said...

I think you will enjoy watching this interview with Sen. Inhofe from last week: http://littlegreenfootballs.com/article/40071_Rachel_Maddow_Interviews_James_Inhofe_Face_of_the_Anti-Science_Right

To summarize, Schools are "brainwashing" our children about climate science and evolution, science curricula should be set not by scientists but by politicians!

Igor Fridman said...

Also, the part of Manoharan's "designer" graphene that's most interesting: Berry phase (disruption of)

the_sparrow's_tail said...

I think my problem with the 'nanoart' is that there is little creative skill involved to produce these FIB patterns, since all the programming is is just inputting a bitmap image with a 0 to 256 grayscale applied. I agree that as an outreach to help people understand how a FIB works this is a useful tool (I have used it in demonstrations myself), but I do not see the art in poorly reproducing famous images.

What would be truly interesting and I might actually peruse this would be to use the FIB and SEM to pattern novel structures that are artistic, and take advantage of the sculptural abilities of charged beam patterning. But again I will need to discuss with our unit leader.... but the outreach group does have some impressive sway....