Wednesday, February 21, 2018

Mathematical Haiku

(Thanks to Paul Glendinning for the Twitter 'mention', from which I learned that my haiku made it into the article.)

What Happens in Knoxville Stays in Knoxville

I'll be heading to my first visit to Tennessee to participate in a NIMBioS working group at University of Tennessee.

I'd try to link to a relevant website, except that my internet connection at the airport is glacially slow, so I'm not going to even try for now. We'll be formulating some forward-looking big problems in network neuroscience to think about together and then hopefully start thinking deeply about and trying to solve.

Update: Here is the link to our working group.

Tuesday, February 20, 2018

Danger in the Nth Dimension: A 1950s Comic with N = 4

The cover of this 1950s comic book is adorable.

And this was with only a 4th dimension!

This will be great fodder for some math and physics talks... "NO! Don't enter that manifold!"

(Tip of the cap to James Gleick.)

Monday, February 19, 2018

Tales from the ArXiv: Building on "Seminal but Laconic" Findings

I am highly amused by one of the sentences in the abstract of this paper, which is called "Systematic elimination of Stokes divergences emanating from complex phase space caustics".

The sentence in the abstract reads as follows: Building on the seminal but laconic findings of Adachi, we show that the deviation from second order can be used to rigorously determine the Stokes lines and therefore the region of the space that should be removed.

I think I need to steal the first part of that sentence, and I know that I have felt that way on many occasions (e.g., with respect to work by Nesterenko) in my career.

"Neither Global nor Local: Heterogeneous Connectivity in Spatial Network Structures of World Migration"

One of my papers, which has had a DOI for about half a year, finally has its final publication coordinates. Notably, this is my first paper in a sociology journal. Here are some details.

Title: Neither Global nor Local: Heterogeneous Connectivity in Spatial Network Structures of World Migration

Authors: Valentin Danchev and Mason A. Porterc

Abstract: For a long time, geographic regions were considered the dominant spatial arbiter of international migration of people. However, since the late 1970s, many scholars have argued that movements reach beyond contiguous regions to connect distant, dispersed, and previously disconnected countries across the globe. The precise structure of world migration, however, remains an open question. We apply network analysis that incorporates spatial information to international migration-stock data to examine what multilateral structures of world migration have emerged from the interplay of regional concentration (local cohesion)and global interconnectedness (global cohesion) for the period 1960–2000. In the world migration network (WMN), nodes represent countries located in geographic space, and edges represent migrants froman origin country who live in a destination country during each decade. We characterize the large-scale structure and evolution of the WMN by algorithmically detecting international migration communities (i.e., sets of countries that are densely connected via migration) using a generalized modularity function for spatial, temporal, and directed networks. Our findings for the whole network suggest that movements in the WMN deviate significantly from the regional boundaries of the world and that international migration communities have become globally interconnected over time. However, we observe a strong variability in the distribution of strengths, neighborhood overlaps, and lengths of migration edges in the WMN. This manifests as three types of communities: global, local, and glocal. We find that long-distance movements in global communities bridge multiple non-contiguous countries, whereas local (and, to a lesser extent, glocal) communities remain trapped in contiguous geographic regions (or neighboring regions) for almost the whole period, contributing to a spatially fragmented WMN. Our findings demonstrate that world migration is neither regionally concentrated nor globally interconnected, but instead exhibits a heterogeneous connectivity pattern that channels unequal migration opportunities across the world.

Wednesday, February 14, 2018

Tales from the ArXiv: "The Random Walk of Cars and Their Collision Probabilities with Planets"

Well, the title of this paper pretty much says it all.

However, there are also some choice quotes in the paper. For example, I really like this deadpan sentence: We now turn to the long-term dynamical evolution for which we integrate 240 realizations of the Tesla for 3.5 Myr into the future.

The final part of the abstract is also nice: By running a large ensemble of simulations with slightly perturbed initial conditions, we estimate the probability of a collision with Earth and Venus over the next one million years to be 6% and 2.5%, respectively. We estimate the dynamical lifetime of the Tesla to be a few tens of millions of years. (I guess the simulation of 3.5 million years wasn't long enough.)

(Tip of the cap to Predrag Cvitanovic.)

Physics Fashion Police: Save the Pocket Protector

Well, this is a bit awkward.

(Tip of the cap to John Dudley.)

Tuesday, February 13, 2018

"Direct Measurement of Superdiffusive Energy Transport in Disordered Granular Chains"

Our paper in which we — after many years of effort — showed strongly nonlinear Anderson phenomena in experiments is finally out in published form!

Here are some details.

Title: Direct Measurement of Superdiffusive Energy Transport in Disordered Granular Chains

Authors: Eunho Kim, Alejandro J. Martínez, Sean E. Phenisee, Panayotis G. Kevrekidis, Mason A. Porter, and Jinkyu Yang

Teaser: Wave propagation is often nonlinear in character, yet the interplay between disorder and nonlinearity remains elusive. Kim et al. use experiments and corroborating numerical simulations to investigate this phenomenon and demonstrate superdiffusive energy transport in disordered granular chains.

Abstract: Energy transport properties in heterogeneous materials have attracted scientific interest for more than half of a century, and they continue to offer fundamental and rich questions. One of the outstanding challenges is to extend Anderson theory for uncorrelated and fully disordered lattices in condensed-matter systems to physical settings in which additional effects compete with disorder. Here we present the first systematic experimental study of energy transport and localization properties in simultaneously disordered and nonlinear granular crystals. In line with prior theoretical studies, we observe in our experiments that disorder and nonlinearity—which individually favor energy localization—can effectively cancel each other out, resulting in the destruction of wave localization. We also show that the combined effect of disorder and nonlinearity can enable manipulation of energy transport speed in granular crystals. Specifically, we experimentally demonstrate superdiffusive transport. Furthermore, our numerical computations suggest that subdiffusive transport should be attainable by controlling the strength of the system’s external precompression force.

Thursday, February 08, 2018

Beware of "Echolocating Insectivorous Hats"


(Tip of the cap to Jennifer Ouelette.)

Sunday, February 04, 2018

Tolkienesque Maps of National Parks

I approve!

Please, please, please can we do this for university campus maps? That would be so awesome!

(Tip of the cap to Peter Dodds.)

Friday, February 02, 2018

An ASCII Soliton Collision

I promised this to some of my Ph.D. students, so I drew it, and I'm posting it here as well.

Thursday, February 01, 2018


I still love the result of this ‘emotion analysis’ of the profile pictures of mathematicians on Twitter.

In addition to these three categories, no face is detected in 24 images.

A Dozen Ways to Divide the United Kingdom

There is some great snark in here!

(Tip of the cap to Melina Freitag.)

Monday, January 29, 2018

"Compass Grass" (aka "Clock Grass")

This is amazing.

Wednesday, January 24, 2018

Chipper Jones, Jim Thome, Vladimir Guerrero, and Trevor Hoffman Elected to Baseball Hall of Fame!

Chipper Jones, Jim Thome, Vladimir Guerrero, and Trevor Hoffman have been elected to Baseball's Hall of Fame! This follows the pre-announcement polling, which I have been following carefully. They join Alan Trammell and Jack Morris, who were inducted last month by the Modern Era Committee.

Jones and Thome were in their first year of eligibility, Guerrero was in his second, and Hoffman was in his third. I thought Thome might squeak through this year, but I wasn't sure if he'd make it in his ballot debut, and he ended up sailing through with close to 90% of the vote. Jones was on 97.2% of the ballots; this is one of the highest totals in history and doesn't come as any surprise at all. Guerrero jumped to more than 90% of the vote (similar to Roberto Alomar's 2nd-year entry to the Hall years before), so it seems there were a bunch of writers who feel he's a Hall of Famer but not somebody who should enter on the first ballot. Trevor Hoffmann ended up with 79.9% of the vote.

Several people made great gains. Importantly, Edgar Martínez squeaked just past 70% of the vote, and it looks like he'll finally make it in 2019, his last year of eligibility through election by the writers. Mike Mussina jumped from the low 50s to 63.5%, and I think he has an outside shot to make it next year (and he'll certainly make it in 2020). Roger Clemens and Barry Bonds went up a bit, and the only reason they're not in already is because of their extracurricular activities. They will have to wait for some other mechanism, as they're only inching upward. Curt Schilling got back over 50% of the vote, and he'll eventually make it. Both he and Mussina should have been elected to the Hall of Fame years ago, but the writers seem not to be very good at recognizing the quality of many starting pitchers.
Omar Vizquel, who got about 37% of the vote, will get to become the new Jack Morris, so people will be arguing about him for many years. He'll eventually make the Hall, but I don't think he deserves it. Larry Walker got a nice jump to 34.1%, but he's in his 8th year of eligibility, so I think he'll have to wait for some sort of veterans committee. I think he'll make it eventually, and his path is resembling that of Alan Trammell, though it looks like Walker is on the way to doing slightly better than Trammell on his final vote totals.

Among the newcomers who are expected to be in the 2019 Hall of Fame ballot, Mariano Rivera will obviously make it on the first ballot. He's the only newcomer who clearly is going to get elected next year. Roy Halladay deserves to make it and will get a bunch of votes, but I think he'll have to wait a bit, especially with his relatively low win total and how tough it's usually been for starting pitchers to get elected during the past couple of decades. It will be interesting to see how many votes Lance Berkman and Roy Oswalt get. I think Roy Oswalt, who doesn't deserve entry, will not even get the 5% to stay on the ballot. I suspect that Berkman will be underappreciated, but I think he had a Hall of Fame peak (though he falls short on peak length and counting numbers). Miguel Tejada is another interesting player to watch; I think he'll get enough votes to stay on the ballot, though I think he falls short of meriting a spot in the Hall. I think that Todd Helton belongs in the Hall of Fame, but I suspect it's going to take some time. (He may end up with a similar road as Larry Walker, and I think both will ultimately enter the Hall of Fame.) There's also Andy Pettitte, who will probably get a nontrivial (though not horribly high) number of votes, though I don't think he deserves to make it. Maybe he'll become the new Jack Morris?

Update: Here is David Schoenfield's list of winners and losers from today's Hall of Fame results.

Monday, January 22, 2018

How Not to Write a Mathematics Paper: Snarky Edition

Here are some brilliant tips for aspiring mathematics authors!

I don't think I've ever encountered this page before. It's hard to find a favorite. There's also lots of great snark in the explanatory notes.

Here is one bit of snark: "One practical criticism applies to this book as well as a large part of contemporary mathematical production: the various statements are called by different names, such as Lemma, Theorem, Proposition, Corollary; the first three are numbered independently of each other, while the numbers assigned to corollaries are functions of several variables; in addition, numbered formulae have their own separate numeration. The strain placed on the reader by this partial ordering is obvious, but apparently readers seek vengeance on other readers when they turn into authors."

(Tip of the cap to @mathematicsprof.)

Saturday, January 20, 2018

It's Still Billy Joel to Me: H. P. Lovecraft Edition

I am highly amused by this connection between Billy Joel's "Piano Man" and H. P. Lovecraft's "Nemesis". Seriously, this is worth a listen. The top one is great!

Though it's still Billy Joel to me!

(Tip of the cap to Todd Wilkinson.)

Friday, January 19, 2018

Headline of the Day: Well Played

Look closely at the various ways that one can parse this headline. ;)

(Tip of the cap to David Kung.)

Monday, January 15, 2018

Bookstore Snark: I Approve!

Here's some really nice snark from the people who run a Cleveland bookstore.

XKCD: Memorable Quotes

I approve of the new xkcd!

Friday, January 12, 2018

"Synergistic Effects in Threshold Models on Networks"

One of my papers just came out in final form today. Here are the details.

Title: Synergistic Effects in Threshold Models on Networks

Authors: Jonas S. Juul, and Mason A. Porter

Abstract: Network structure can have a significant impact on the propagation of diseases, memes, and information on social networks. Different types of spreading processes (and other dynamical processes) are affected by network architecture in different ways, and it is important to develop tractable models of spreading processes on networks to explore such issues. In this paper, we incorporate the idea of synergy into a two-state ("active" or "passive") threshold model of social influence on networks. Our model’s update rule is deterministic, and the influence of each meme-carrying (i.e., active) neighbor can—depending on a parameter—either be enhanced or inhibited by an amount that depends on the number of active neighbors of a node. Such a synergistic system models social behavior in which the willingness to adopt either accelerates or saturates in a way that depends on the number of neighbors who have adopted that behavior. We illustrate that our model’s synergy parameter has a crucial effect on system dynamics, as it determines whether degree-k nodes are possible or impossible to activate. We simulate synergistic meme spreading on both random-graph models and networks constructed from empirical data. Using a heterogeneous mean-field approximation, which we derive under the assumption that a network is locally treelike, we are able to determine which synergy-parameter values allow degree-k nodes to be activated for many networks and for a broad family of synergistic models.

Thursday, January 11, 2018

Up-Goer Five Text Editor

If any of you want to try explaining an idea using only the ten hundred most common words in the English language, you can try at this page.

(Tip of the cap to Lan Ma.)

Tuesday, January 09, 2018

What Happens at the Joint Mathematics Meetings Stays at the Joint Mathematics Meetings (2018 Edition)

I'm on the train to head to San Diego for the 2018 Joint Mathematics Meetings. I'm really excited about it! Among other things, there are more sessions related to things like networks and data than ever before at this conference. And I always like seeing my many peeps from the mathematics world, including friends who I don't get to see at conferences on more specific topics.

Update: Here is a short video of some nice scenery during my train ride from Los Angeles to San Diego. Below is a still shot that I took just before the video and also a picture of me and a statue of the late, great Tony Gwynn.

And, finally, here is my tweet after I arrived.

Saturday, January 06, 2018

Friday, January 05, 2018

For Good Weather, Call Jenny


(Tip of the cap to Bruno Gonçalves.)

Thursday, January 04, 2018

Also in Physics Today: Mary Somerville!

In my obsession yesterday with the article about the physics of croissants (which has a lovely picture of a croissant network) from the same issue, I failed to notice that the cover article in the January 2018 issue of Physics Today is about Mary Somerville. Here is the cover.

The Problem With Talking to People

There are two things that I really dislike about talking to people: (1) talking and (2) people.

Wednesday, January 03, 2018

The Physics of Croissants

The January 2018 issue of Physics Today has a short article about the physics of croissants. Yummy!

Also, check out the lovely contact network in the two-dimensional contact network that one can see in the picture.

Update: Great minds think alike!

Monday, January 01, 2018

Calligraphy in an Old Edition of The Lady of Shalott

I recommend looking at this calligraphy while listening to Loreena McKennitt in the background. (And this is one of her very best songs, which is saying a lot.)

(Tip of the cap to Sydney Padua.)