Announcing the Nano Networks blog

As one of my volunteer service positions, I am chair of the IEEE ComSoc Emerging Technologies Subcommittee on Nanoscale, Molecular, and Quantum Networking.  I've decided to transform our committee's home page into a blog, to share research news and other details about this field.

You can read the blog at http://nano-networks.blogspot.com/.  You can also subscribe to our Twitter feed: @NanoNetworks.

The blog will be newsletter-style; if you have anything interesting to post (new paper, profile of yourself or your lab, upcoming conference, or anything else), please send me a short blurb, preferably something ready to post.  I will try to make use of anything sent to me.

Entropy fact of the day

It's well known that certain distributions have maximum entropy under moment constraints. For instance, maximum entropy H(X) under a variance constraint is given by the Gaussian distribution. Generally, for any positive integer k and for given constant c, there exist algorithms to find the distribution maximizing H(X) subject to E[X^k] = c.

However, here's what I learned yesterday: if we change the constraint to E[X^-k] = c, there exists no such maximum entropy distribution -- because you can always achieve unbounded entropy subject to the constraint.

At first I thought this was surprising, but then I realized it's not too hard to think of an example that shows why it's true. Think about it for a few minutes -- I'll post a hint in the comments.

How to get my attention

Every couple of months or so, a wave of emails from prospective PhD applicants will flood my inbox. A typical email will go something like this:

Dear Professor Andrew Eckford,

I saw your web page and am very interested in your research on computer networks. I have the same research interests as you and would like to apply for a PhD position under your supervision. My master's thesis was entitled "[topic I'm not interested in]" and I published my results in [conference/journal I've never heard of]. I am attaching my resume to this email and look forward to your positive reply.

The messages are so similar, both in terms of content and geographic origin, that I have to think there is some agency behind them. But particularly because they are so similar, it's easy to dismiss them as spam and ignore them. It probably doesn't hurt an applicant to send these emails, but I would never remember such a message at admission time, so it certainly doesn't help either.

What would get my attention is an applicant who makes it clear that s/he is not just interested in the PhD slot. In fact it's probably unnecessary to mention in the first email that you're a Ph.D. applicant; what I really want are bright students who are interested in research in general, and my research in particular. I've never received an email like this from an applicant, but I would certainly remember it if I did:

Dear Professor, I read your recent papers on fractional cooperation, and thought the idea was interesting. I have the following comments and questions about your scheme ... [some insightful commentary follows].

Of course, a more personal touch works for me, because my group is small and I can afford to be very selective with my Ph.D. applicants. Maybe the form letter approach works for profs whose groups are measured in the dozens.