Monthly Archives: July 2009

Rationing healthcare

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A recurring link in my facebook feed today was to an article in the NY Times Magazine on rationing health care. It’s worth reading, but the this made me squirm a bit:

But even in emergency rooms, people without health insurance may receive less health care than those with insurance. Joseph Doyle, a professor of economics at the Sloan School of Management at M.I.T., studied the records of people in Wisconsin who were injured in severe automobile accidents and had no choice but to go to the hospital. He estimated that those who had no health insurance received 20 percent less care and had a death rate 37 percent higher than those with health insurance. This difference held up even when those without health insurance were compared with those without automobile insurance, and with those on Medicaid — groups with whom they share some characteristics that might affect treatment. The lack of insurance seems to be what caused the greater number of deaths.

Oh correlation/causation fallacy, I long for your demise. At least he said “seems.”

Hangwringing about conference blogging from Nature

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Lav pointed out this article in Nature on concerns over blogging about talks at conferences. It contains gems such as:

“I could take pictures of every slide and it would be on the Internet within seconds.” — Lars Jensen

and

MacArthur’s comprehensive postings were read by many scientists but they irked journalists attending the meeting. The meeting rules stated that reporters had to seek permission from speakers before publishing material on their work…

and

This kind of direct-to-web exposure creates problems for many industrial and applied researchers. In the United States, patent applications must be filed within a year of any information becoming available to the public. The exact date of that ‘public disclosure’ used to be difficult to nail down, but no more, says Michael Natan, chief executive officer of Oxonica Materials, a nanotechnology company in Mountain View, California. In the Internet age, time-stamped photographs of a talk can let competitors know the exact minute a researcher presented a patentable result. Consequently, “people in industry will be much more circumspect about what they present in public”, he says.

So I know I don’t work on Science (with a capital S) and that a I’m not the most knowledgeable guy out there. I do know from talking to friends that there is sometime shady behavior involving scooping of other labs by stealing ideas and fast-tracking a paper, but this article is a bit too paranoid.

  • Industry is already circumspect about what they present in public. I don’t think blogging is going to make them any more paranoid — patent firms already hire PhD engineers to comb the conference proceedings and literature to prove ideas were disclosed publically or invented too early in order to limit the scope of patents.
  • Who the hell would take pictures of every slide? Lars Jensen himself thinks it’s ridiculous (see the comments on the article) and the reporter here is definitely ginning up the controversy.
  • Going to a conference and talking publicly about your research is public disclosure. Sorry dudes, but we should not indulge in Clintonian verbal acrobatics.
  • If Cold Spring Harbor wants to force journalists to abide by ridiculous disclosure rules, then they should do what MILCOM does and have classified sessions.

Romanian diacritics

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I came across this blog post today while trying to figure out how to write the Romanian breve (the symbol ă) in a document, and it was an amusingly angry rant about Romanian orthography. The fact that the Romanian currency even got it wrong is pretty funny. But it seems a bit like a futile battle; things always change and I bet the orthography gets merged eventually. I, for one, miss the ess-zett (ß) in German, but it’s gone the way of the dinosaurs.

That would be a great name for an diacritic mark — a dinosaur. A stegosaurus sitting on top of a U. But how would it be pronounced?

ISIT : first set of talks

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Outer Bounds for User Cooperation
Ravi Tandon, Sennur Ulukus

This paper looked converse bounds for the MAC with generalized feedback. By applying the dependence balance bound, one can get an outer bound for the capacity region in terms of auxiliary random variables whose cardinality is difficult to bound. For a specific form of the channel, the “user cooperation channel.” where the feedback signals to the users are made from noisy versions of the other users’s signal, they find a way to evaluate the bound by looking at all input densities satisfying the constraints and then arguing that it is sufficient to consider Gaussian densities. The resulting bound matches the full-cooperation and no-cooperation bound when taking the respective limits in the feedback noise, and is tighter than the cutset bound.

Optimal Quantization of Random Measurements in Compressed Sensing
John Sun, Vivek Goyal

The goal here was to design a quantizer for noisy measurements in compressed sensing, while keeping the decoder/reconstructor fixed. This was done in the same high rate scalar quantization setting that I’d seen in other talks, with point-density functions to represent the reconstruction points. They draw a connection to the earlier work on functional scalar quantization and find optimal quantizers for the Lasso. They used an recent called “homotopy continuation,” which looks at the solution produced by the Lasso as a function of the regularization parameter, which I should probably read up on a bit more…

A Sparsity Detection Framework for On-Off Random Access Channels
Sundeep Rangan, Alyson Fletcher, Vivek Goyal

This looked at a MAC with n users and the decoder wants to detect which users transmitted. The users are each “on” with some fixed probability, and they show this can be put into a sparsity detection framework. There are two problems to overcome — the near-far effect of large dynamic range of the received signals, and a “multiaccess interference” (MAI) phenomenon that plagues most detection algorithms, including the Lasso and orthogonal matching pursuit (OMP). The question is whether a practical algorithm can overcome these effects — they show that a modification of OMP can do so as long as the decoder knows some additional information about the received signals, namely the power profile which is the order of the users’ power, conditional that they are active.

Eigen-Beamforming with Delayed Feedback and Channel Prediction
Tr Ramya, Srikrishna Bhashyam

This paper looked at the effect of delay in the feedback link in a system that is trying to do beamforming. The main effect of delay is that there is a mismatch between CSIT and CSIR. There is also the effect of channel estimation error. One solution is to do some channel prediction at the encoder, and they show that delayed feedback can affect the diversity order, while prediction can help improve the performance. Unfortunately, at high Doppler shift and and high SNR, the prediction filter becomes too complex. I hadn’t really seen much work on the effect of longer delay in feedback, so this was an interesting set of ideas for me.

ISIT 2009 : plenaries and the Shannon Award

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As I mentioned earlier, Rich Baraniuk’s plenary was quite energetic and entertaining. David Tse gave the next plenary, called It’s Easier to Approximate, mainly building on his recent string of work with Raul Etkin, Hua Wang, Suhas Diggavi, Salman Avestimehr, Guy Bresler, Changho Suh, and Mohammad Ali Maddah-Ali (and others too I imagine). He motivated the idea of using deterministic models for multiterminal Gaussian problems essentially by appealing to the idea of building approximation algorithms, although the connection directly to that community wasn’t made as explicitly (c.f. Michelle Effros’s plenary). David is also a great speaker, so even though I had seen a lot of these results before from being at Berkeley, the talk helped really put it all together. Raymond Yeung gave another great talk on information inequalities and for the first time I think I understood the point of “non-Shannon information inequalities” in terms of their connections to other disciplines. Hopefully I’ll get around to posting something about the automatic inequality provers out there. Unfortunately I missed all of Friday, so I didn’t get to see Noga Alon‘s plenary, but I’m sure it was great too. Does anyone else care to comment?

The Shannon Lecture was given, of course, by Jorma Rissanen, and it was on a basic question in statistics : model selection. Rissanen developed the Minimum Description Length (MDL) principle, which I had always understood in a fuzzy sense to mean that you choose a model which is easy to describe information theoretically, but I never had a good handle on what that meant besides taking some logs. The talk was peppered with good bits of philosophy. One which stood out to me was that our insistence that there be a “true model” for the data often leads to problems. That is, sometimes we’re better off not assuming that the data was generating according to a particular model, but focus on finding the best model that fits the data in our class. I got to chat with Rissanen later about this and pointed out that it’s a bit like religion to assume an underlying true distribution. Another great tidbit was his claim that “nonparametric models are nonsense,” by which he meant that essentially every model is parametric — it’s just that sometimes the number of parameters is mind-bogglingly huge. The most interesting thing is that there were new results in the Shannon lecture, and Rissanen is working on a paper with those results now!

The big news was of course that Te Sun Han is going to be next year’s Shannon Awardee. I was very happy to hear this — I’ve been hoping he would win it for a while now, so I had a big grin on my face leaving the banquet…

ArXiV is down

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I got the following from ArXiV today:

Submissions to arXiv have been disabled for maintenance. arXiv’s database is down for maintenance. It is still possible to browse, view and search papers that have already been announced but submissions and replacements disabled, as are the functions to add cross listings and journal references.

So I guess I’ll have to wait to post our new submission, “Privacy constraints in regularized convex optimization,” until the system comes back up.

In the meantime, I’ll blog a bit about ISIT!