What Happens at Caltech Stays at Caltech

You want an awesome ‪#‎tbt ('Throwback Thursday')‬? OK, I'll give you an awesome #tbt!

Tomorrow, I am flying out to Pasadena to attend a reunion/workshop for the 20th anniversary of the CDS* department at Caltech!

And I have even packed my faded 20-year old Lloyd shirt that I got ... [all together now] ... when I was frosh at Caltech in Fall 1994.

* Control and Dynamical Systems (not TFM)

Origin of Mysterious World Trade Center Ship

I missed this story previously, but the remains of an old ship was unearthed under the collapsed World Trade Center in 2010, and now scientists believe that they know the origin of this ship. It seems to have been built from trees that were felled in Pennsylvania in 1773. Very cool!

Also, I love the description of the scientific article that reported the discovery as "probably the most attention grabbing story ever published in Tree-Ring Research".

Vin Scully to Continue Broadcasting Dodger Games in 2015!!!!

It's become an annual rite during the Major League Baseball season. Vin Scully takes his time to figure out if he'll continue broadcasting Dodger games the next year, and yesterday the Dodgers announced that Vin will continue broadcasting games for them in 2015. Awesome!!!!

(Tip of the cap to whoever posts for 'Vin Scully' and MLB on Facebook.)

XKCD on Chaos: "Can You Do That Weird Laugh?"

The topic for today's XKCD is chaos, which is of course near and dear to my heart. I love the mouseover: "Although the oral exam for the doctorate was just 'can you do that weird laugh?'"

Hmmm... I got my PhD in quantum chaos, and I never got that question on my oral exam to defend my thesis. :(

Achievement Unlocked: Construct Infinite Loop in \Latex

Until just now, I never realized that it was possible to construct an infinite loop in \Latex. But it is, and an infinite loop is indeed an understandable outcome of the following text: \newcommand{\lcm}{\mbox{\lcm}}", which I of course obtained via the magic of 'replace all'. It turns out that my \Latex compiler (TeXShop) apparently has an automatic abort for such situations.

3D Printed Version of the Zachary Karate Club

Thanks to Renaud Lambiotte for creating a 3D-printed version of the Zachary Karate Club and sending it to me as a gift.

Sadly, it didn't survive snail mail, and this algorithm resulted in what is clearly a suboptimal partition.

Tales from the ArXiv: "Deep Community Detection"

This paper, called "Deep Community Detection", makes me want to write a paper called "Shallow Community Detection". It's now officially on my list. One thing that is great about the title is that there is an inherent grammatical ambiguity regarding whether the authors are detecting deep communities (which is what they have in mind) or whether the community detection that they are performing is deep. That is why I like the title.

Also, I love Fig. 8. Once again, the Porter-Mucha-Warmbrand 3-clique makes an appearance in a paper figure. (It occurred in a Physical Review E paper earlier this year, and I got the honor of being an initial condition for that other paper.)

George Harrison Memorial Tree Killed by Actual Beetles

In what may be one of the most ironic things ever, a Memorial Tree for George Harrison died as a result of a beetle infestation. D'oh!

Dueling to the Death to Prove a Theorem

Whoever posts items on Facebook for MATLAB posted this fascinating article on 10 of the maddest scientists who ever lived. My favorite line in this article comes from the blurb about Kevin Warwick:

Research is meant to be risky, transgressive, and unsettling, and Warwick reminds us that there are still scientists out there who would probably duel to the death to prove a theorem.

Here, here!

Domestication and Floppiness

Here is a very cool article that explains a new hypothesis about why so many domesticated animals have floppy ears.

"Multilayer Networks"

Our mega-review article on multilayer networks is finally out! The page proof stage was particularly painful, so it's great that the published version of our article is now available. (In my Facebook post, I wrote "After a long and painful bout with page proofs". Reading my words now, it's like "page proofs" are a disease, thought that allusion is not what I intended when I wrote that text.) We don't have things like page numbers yet, but those will come. (By the way, "our" equals the PLEXMATH team.)

Here are the details about the article.


Title: Multilayer Networks

Authors: Mikko Kivelä, Alex Arenas, Marc Barthelemy, James P. Gleeson, Yamir Moreno, and Mason A. Porter

Abstract: In most natural and engineered systems, a set of entities interact with each other in complicated patterns that can encompass multiple types of relationships, change in time and include other types of complications. Such systems include multiple subsystems and layers of connectivity, and it is important to take such ‘multilayer’ features into account to try to improve our understanding of complex systems. Consequently, it is necessary to generalize 'traditional' network theory by developing (and validating) a framework and associated tools to study multilayer systems in a comprehensive fashion. The origins of such efforts date back several decades and arose in multiple disciplines, and now the study of multilayer networks has become one of the most important directions in network science. In this paper, we discuss the history of multilayer networks (and related concepts) and review the exploding body of work on such networks. To unify the disparate terminology in the large body of recent work, we discuss a general framework for multilayer networks, construct a dictionary of terminology to relate the numerous existing concepts to each other and provide a thorough discussion that compares, contrasts and translates between related notions such as multilayer networks, multiplex networks, interdependent networks, networks of networks and many others. We also survey and discuss existing data sets that can be represented as multilayer networks. We review attempts to generalize single-layer-network diagnostics to multilayer networks. We also discuss the rapidly expanding research on multilayer-network models and notions like community structure, connected components, tensor decompositions and various types of dynamical processes on multilayer networks. We conclude with a summary and an outlook.

Drugs and Alcohol Under the Microscope

Here are some pictures of drugs and pictures of alcohol under a microscope.

I previously blogged about what alcohol looks like under a microscope.

"GER... ARG"

As Dave Relyea has pointed out: For all Buffy fans: The world cup final has a scoreboard, and it reads: "GER... ARG".

I approve!

What Happens in Silwood Park Stays in Silwood Park

This evening, I'll be taking the train (and, apparently, replacement bus service) to Ascot to get myself over to Imperial College's Silwood Park campus for environmental fluctuations, recovery, and resilience of biological networks, which is part of their program on Grand Challenges in the Ecosystem and the Environment (GCEE).

Take a look at a a map of the local area, which covers Silwood, Windsor Park, and Maidenhead. Based on the names of some of the places on this map, it looks like I'm going to be pretty close to a Hellmouth. Also, this map is a great example of how awesome the Brits can be sometimes with their naming conventions. It would be pretty damn awesome, for example, if "Cheapside" has evolved to be a posh, expensive location filled with luxurious mansions. ("Unfortunately, I can't afford to live in Cheapside.")

Update: I have reached the center for population biology that Imperial College has at their Silkwood Park campus, and there are rabbits all over the place here. There is something right with the world.

"A Simple Generative Model of Collective Online Behavior"

Last Monday, PNAS published, in their early edition (so there are no volume or page numbers yet), a new article by my collaborators and me about how to model complex systems in a way that incorporates data directly into a simple model. We also illustrate with this example a nice situation in which several different situations (in particular, different parameter values, where one gets different qualitative mechanisms in different regions of parameter space) give the same qualitative long-time behavior (and very similar quantitative long-time behavior) so that one needs to consider the temporal dynamics explicitly to distinguish between the mechanisms. There are many papers that seem to assume mechanisms based on statistical fitting of long-time (or even equilibrium) behavior, and that is very dangerous. Here are the details about the article.


Title: A Simple Generative Model of Collective Online Behavior

Authors: James P. Gleesona, Davide Cellai, Jukka-Pekka Onnela, Mason A. Porter, and Felix Reed-Tsochas

Abstract: Human activities increasingly take place in online environments, providing novel opportunities for relating individual behaviors to population-level outcomes. In this paper, we introduce a simple generative model for the collective behavior of millions of social networking site users who are deciding between different software applications. Our model incorporates two distinct mechanisms: one is associated with recent decisions of users, and the other reflects the cumulative popularity of each application. Importantly, although various combinations of the two mechanisms yield long-time behavior that is consistent with data, the only models that reproduce the observed temporal dynamics are those that strongly emphasize the recent popularity of applications over their cumulative popularity. This demonstrates--even when using purely observational data without experimental design--that temporal data-driven modeling can effectively distinguish between competing microscopic mechanisms, allowing us to uncover previously unidentified aspects of collective online behavior.

Significance Paragraph (which is now a part of PNAS papers): One of the most common strategies in studying complex systems is to investigate and interpret whether any "hidden order" is present by fitting observed statistical regularities via data analysis and then reproducing such regularities with long-time or equilibrium dynamics fromsome generative model. Unfortunately, many different models can possess indistinguishable long-time dynamics, so the above recipe is often insufficient to discern the relative quality of competing models. In this paper, we use the example of collective online behavior to illustrate that, by contrast, time-dependent modeling can be very effective at disentangling competing generative models of a complex system.


This paper has gotten a little bit of press coverage. You can find links to press coverage for this article (and other articles of mine) on the press part of my web page.

"Peer Review Ring" Busted

A "peer review ring" (kind of like a prostitution ring, except with more scientists) at Journal of Vibration and Control has been busted. The situation is described in this article, and you can find more information about this peer-review scandal in this article.

The now-former Editor in Chief of JVC is Ali Nayfeh, who has written some very nice books on nonlinear vibrations. (I have one of his books. There is some really good stuff in there.) He has apparently "retired" as EiC, though my expectation is that it is a combination of genuine retirement and embarrassment that this scandal took place on his watch.

The choice quote comes from Retraction Watch, who started their report in the busting of the peer-review ring with "This one deserves a 'wow.'"

(Tip of the cap to Jennifer Nicoll Victor.)

3D Fractal Sculptures

These fractal sculptures look awesome!

Tending Towards Infinity

At the conference I am attending, I just saw a t-shirt with the text "Old mathematicians don't die, they just tend to infinity." I approve!

Well, the grammar could be better --- there should be a semicolon instead of a comma --- but I still love the shirt.

Monday Cricketblogging

Here are some pictures of me playing cricket last Friday. Also notice that I am consuming ice cream in the team photo (and that the number 137 was requested with complete forethought and malice).

What Happens in Madrid Stays in Madrid

I have arrived in Madrid for the 10th AIMS Conference on Differential Equations, Dynamical Systems, and Applications.

The internet at this hotel is painfully slow. :(

Let's Call The Whole Thing Off

You say "universality"
I say "bullshit"
Let's call the whole thing off.

This is inspired by this song, obviously.

Rogue Demon Hunters (For Real)

Yes, really.

For a Good Time, Call (Desmond) Jennings

Joe Maddon has decided to tip his cap to Tommy Tutone for the Ray's lineup tonight. I approve!

Well, technically, there are a few additional digits in the lineup and I don't remember '0' being used for the DH position before --- but points to Joe Maddon for doing this on purpose! That's the type of thing I would do. :)

Remember, the magic digits are 867-5309. And if you ever call that phone number --- no matter what timezone you're in --- make sure to ask for "Jenny".

(Tip of the cap to whoever posts for MLB on Facebook, though I didn't realize from their post that Joe Maddon did this on purpose. I am linking to a different article than the one from their post.)

Revenge of the Carnivorous Flying Squirrel

The carnivorous flying squirrel is real (and not just a private D & D joke between one of my friends and me). I think I rolled more critical hits in the infamous CFSA incident, which was from my first time as a dungeon master, then I have any time since.

I have seen the CFS, which appeared in Monster Manual II in the first edition of AD & D, in discussions of the lamest D & D creatures. Here is a Pathfinder version of this critter.

Tales from the ArXiv: Predicting Talk Attendance at Conferences

This paper discusses the predictability of talk attendance at conferences.

I think it depends: Is the conference in Snowbird or Maui? :)

The one time we had a SIAM dynamical systems conference in Maui, the attendance as a function of time was, in one word, "impressive". I did make an important connection that I am pretty sure led to my postdoc job at Georgia Tech. The lesson here is clear: attend conferences in Maui.

A Spectral Navigation Algorithm

Clearly, some users of London's transportation system are using a spectral algorithm for navigation.

(Tip of the cap to Sang Hoon Lee.)

Pictures from the Networks MRC

Here are some pictures from the inaugural workshop of the Mathematics Research Community on Network Science.

Recall: I was at Snowbird in an even year!