Jonah Golberg is pantsed by Jon Stewart

Over the last few weeks I’ve been reading Sadly, No! document the atrocities of Jonah Goldberg’s new book Liberal Fascism : The Secret History of the American Left, From Mussolini to the Politics of Meaning. The book can be summarized by the following argument : Nazis liked organic food. Modern liberals like organic food. Therefore modern liberalism is rooted in fascism. Clever, eh?

Then I found out about this interview of Goldberg on the Daily Show. Wow.

See also this insightful contribution from Michael Bérubé on the line from Dinesh D’Souza (also one of my least favorite “commentators”) to Goldberg.

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honorable mathematical intentions

In looking up a rather obscure paper on list decoding on Project Euclid I noticed that they link bibliography items to the MathSciNet reviews. I figured I’d take a look at the review of Shannon’s famous paper, A mathematical theory of communication. It turns out the review was written by Doob, and contains this little dig:

The discussion is suggestive throughout, rather than mathematical, and it is not always clear that the author’s mathematical intentions are honorable.

I have this image in my mind of Doob as the father of Mathematics, saying in a Southern accent “I’m not sure your intentions towards my daughter are entirely honorable, Mr. Shannon.”

a good excuse

Friends of mine returned from their honeymoon, during which they visited the Sossusvlei sand dunes in Namibia. They went as part of a tour group and there were two planes to take them back, except that one wouldn’t start. So first the pilot of the other plane tried whacking the engine with a hammer. Then they found that the solenoid had broken so they fixed that. Then they saw the battery was dead so they were stuck. The pilot announced that they would have to switch planes because “not enough things are working on this one.”

That strikes me as a good excuse to use for general things — it would all work out if enough things were working, but…

paper a day : Recovery of Time Encoded Bandlimited Signals

Perfect Recovery and Sensitivity Analysis of Time Encoded Bandlimited Signals
Aurel A. Lazar and László T. Tóth
IEEE Transactions on Circuits and Systems – I: Regular Papers, vol. 51, no. 10, October 2004

I heard about this paper from Prakash Narayan, who came to give a seminar at last semester, and I thought it was pretty interesting. In an undergrad signals and systems class we usually spend most of our time talking about converting an analog signal x(t) into a discrete-time signal x[n] by sampling x(t) regularly in time. That is, we set x[n] = x(nT) for some sampling interval T. There are at least two reasons for doing things this way: it’s simple to explain and the math is beautiful. If x(t) is a bandlimited signal, it’s Fourier transform has support only on the interval [-B,B], and the famous Nyquist–Shannon sampling theorem (which goes by many other names) tells us that if 1/T > 2 B the original signal x(t) is recoverable from the sequence x[n]. Since there is all of this beautiful Fourier theory around we can convolve things and show fun properties about linear time-invariant systems with the greatest of ease.

So far so good. But sampling is only half the story in Analog to Digital conversion. Not only should the times be discretized, but the values should also be discretized. In this case we need to use a quantizer on the samples x[n]. Fast, high precision quantizers are expensive, especially at low power. On the other hand, clocks are pretty cheap. The suggestion in this paper is to think about time-encoding mechanisms (TEMs), in which we encode a bandlimited x(t) into a sequence of times {tk}. Another way to think about it is as a signal z(t) taking values +b or -b and switching values at the times {tk}. The disadvantage of this representation is that linear operations on analog signals don’t turn into linear operations on the discrete signals. However, this conversion can be implemented with an adder, integrator, and a noninverting Schmitt trigger that detects when the output of the integrator passes a threshold.

TEM Figure

This paper shows that the circuit above can be implemented in real time and that {tk} are sufficient to reconstruct x(t). The recovery algorithm looks pretty simple — multiplication by a certain pseudoinverse matrix. The second part of the paper deals with the stability of the system with respect to errors in the decoder parameter or time quantization. The compare the scheme to irregular sampling algorithms. The tools they use for this analysis come from non-harmonic analysis, but the math isn’t all that rough.

This work is different than the sampling with a finite rate of innovation work of Vetterli, Marziliano, and Blu, which says (loosely) that regular sampling is good for a wider class of signals than bandlimited signals. It would be interesting to see if a TEM mechanism is good for those signals as well. That might be another robustness issue to explore.

Finally, one interesting connection (and possible another motivation for this work) is that neurons may be doing this kind of time encoding all the time. The integrate-and-fire model of a neuron is, from a black-box perspective, converting an input signal into a sequence of times, just like a TEM.

Choral Internet Radio?

Since I’ve all but abandoned choral singing this year in favor of writing my thesis (and boy does it bum me out), I’m at least trying to get more new old music in my ears. I tend to forget the iPod at home so I’ve turned to internet radio. For a while I was listening to KALX, but it’s not conducive to writing. For a while I was hooked on SomaFM, but no station there is quite what I want to listen to, ever. Then I turned to KKJZ in Long Beach for my jazz fix. I highly recommend it. Anuraag seems to be good for Indian classical music, but there must be other ones out there.

Now I’m itching for some good old vocal polyphony. Chant will do in a pinch. I came across this Choral Treasure station which is ok, but are there alternatives. Perhaps this is something Choralista should be able to tell me about, hmmmm?

[UPDATE: I can’t complain about any radio station that plays the whole Missa Papae Marcelli, so I hope I don’t sound like I’m dissatisfied with Choral Treasure…]

furoshiki madness!

Via Lifehacker, I learned about Furoshiki, a traditional Japanese cloth wrapping. You’re less likely to get paper cuts than with origami, but you still get the fun schematic diagrams.
Apparently the Japanese Environment minister (they have an environment minister? Is that essentially the Dept. of the Interior?) wants to promote the use of them. Although you can buy them from vendors, it’s the sort of thing that screams “DIY.”

Berkeley EECS makes TA-ing more cushy

At the end of last semester I got a memo from our department trying to make TA-ing a more attractive prospect. In reality, a grad student in EECS is a TA here (or Graduate Student Instructor (GSI)) for one of three reasons : they’re a first-year and don’t have an advisor (yet), their advisor is low on funds or doesn’t have funds for their particular project, or they are fulfilling their teaching requirement to graduate (one semester only). The difference between being paid as a TA and as a research assistant (Grad Student Researcher (GSR)) is significant — the union negotiates the pay scale for GSIs, and the University is not going to let salaries rise if they can help it. In some instances a student’s advisor can bump up their salary to the GSR level. So now the department recommends:

  • If you are doing research the same semester you’re teaching, your advisor should give you a partial GSR to help out.
  • You can be appointing as a 100% GSR during winter break if you are around.
  • If your advisor can’t afford to pay you and you are GSI-ing to fulfill the graduation requirement, then the department will give you a unconstrained fellowship.

All in all, it’s seems like a much more pleasant deal — how this will end up changing the dynamics of TAing is unclear though. It also makes things much much nicer in EECS than in other departments, which seems somehow unfair in the end. Why can’t all GSIs get better pay?