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[SOUND EFFECTS] PHILIP GREENSPUN: All right. Let's talk about aircraft ownership and maintenance. Some of this stuff actually, oddly enough, is on the test. What does it cost to own an airplane? Most people say, I can't afford that. But then you see them buy a brand new car or renovate their kitchen for $200,000. So I don't know what their excuse is. It's actually not expensive to own a four-seat airplane. There's so many out there. There were more pilots in the '70s and '80s, when these airplanes were built in large quantities. The owner of East Coast Aero Club, Mark, he says that, in the '80s, there was a waiting list even for a tie down at Hanscom. Now there's ample parking. The hangar space is still a little bit tight, but if you just want to get a Cessna and pay, it's actually a lot cheaper to tie a Cessna down at Hanscom than it is to park a car in Cambridge. And there's plenty of room. He said every firefighter, every tea...

[DIGITAL EFFECTS] PROFESSOR: Welcome back to 8.701. So we'll start a new chapter now, QCD or quantum chromodynamics. And then, this first lecture of this chapter, we talk about the production of hadrons. This is really meant as an introductory lecture, but we will also already see some very interesting and useful concepts. So we want to produce quarks and anti-quark pairs, and we do this electron-positron collisions. We have studied in detail this first part of the diagram. Specifically, we calculated a cross-section of muon and anti-muon production, and we also have seen more changes than we have same kind of particle in the final state of the electron-positron scattering to electron-positrons. So now, we've replaced the muons with our quarks and anti-quark pairs. And the first step, we want to remind ourselves of the available quarks in this discussion. So we have the up quark, the down quark, charm, strange, top, and bottom. You see that the charges are given h...

[DIGITAL EFFECTS] NANCY KANWISHER: So to remind you, we've been talking last week about doing two things at once-- asking all sort of questions of what we might want to know about face perception in the brain-- there are some questions. But at the same time, the agenda has been to consider the different methods available in human cognitive neuroscience and what kinds of questions each one can answer. So last week, we talked about a bunch of them, and today, we're going to wrap this up talking about TMS and animal studies. But first, I just want to remind you very briefly-- I won't go through in excruciating detail-- we talked about behavioral methods, which are great for characterizing internal representations, as you saw with face inversion effects and some of the other behavioral data, they have major disadvantages, which is that with behavior, you're just measuring the output. It's pretty sparse. And from that, you have to infer all the stuff that h...

[SOUND EFFECTS] PROFESSOR: OK, I just want to just highlight your attention to things. Like every day, I get that MIT news feed. I get a couple of other news feeds. And I just thought this was really sort of a striking image and I think a great way to convey science and engineering is through sort of really eye catching imagery. This is a synapse, which is where nerves contact to other nerves or to the neuromuscular junction in order to trigger activity. And this is a piece of research out of the Cima-- whoops, go back one-- whoops, go back one more-- between the Cima and Langer labs, where they've designed little tiny microchip probes. They're about 10 microns big. They can be planted in the brain in different sites, hopefully non-invasively. And they can report on concentrations of this neurotransmitter, dopamine. And the reason you might want to be able to do that is that there is a dopamine deficit in a lot of neurologic disorders. So you would like to underst...