Friday, December 14, 2018

But Are These Data Cookies Reproducible?

I think it's very important to check the reproducibility of these data.

(Tasty, tasty reproducibility.)

(Tip of the cap to Javier Buldú.)

Update: Now that I think of it, "Sweet, sweet reproducibility." would have been better phrasing, given its larger set of allusions.

Wednesday, December 12, 2018

"Variability in Fermi–Pasta–Ulam–Tsingou Arrays Can Prevent Recurrences"

A paper of mine came out in final form today. Here are some details.

Title: "Variability in Fermi–Pasta–Ulam–Tsingou Arrays Can Prevent Recurrences"

Authors: Heather Nelson, Mason A. Porter, and Bhaskar Choubey

Abstract: In 1955, Fermi, Pasta, Ulam, and Tsingou reported recurrence over time of energy between modes in a one-dimensional array of nonlinear oscillators. Subsequently, there have been myriad numerical experiments using homogenous FPUT arrays in the form of chains of ideal, nonlinearly coupled oscillators. However, inherent variations (e.g., due to manufacturing tolerance) introduce heterogeneity into the parameters of any physical system. We demonstrate that such tolerances degrade the observance of recurrences, often leading to complete loss in moderately-sized arrays. We numerically simulate heterogeneous FPUT systems to investigate the effects of tolerances on dynamics. Our results illustrate that tolerances in real nonlinear oscillator arrays may limit the applicability of results from numerical experiments on them to physical systems, unless appropriate heterogeneities are taken into account.

Sunday, December 09, 2018

Lee Smith and Harold Baines Elected to Baseball's Hall of Fame by the Veterans Committee

Lee Smith and Harold Baines were elected to Baseball's Hall of Fame today by "Today's Game Era Committee", an incarnation of the Veterans Committee.

These are not good picks, especially the one of Harold Baines. They belong more in the Hall of Very Good, rather than in the Hall of Fame. They had very good careers and compiled large numbers in various stats, but in my opinion they don't belong in the Hall of Fame. One of the things to think about when considering whether a player raises or lowers the standards of the Hall at their position. In my view, Lee Smith is a borderline case and I would put him just below the border, but he was the all-time saves leader for a while (and, in general, I can see the arguments in his favor), and he got many Hall of Fame votes for years. Thus, I only view this as a mildly bad pick. I understand it, but I wouldn't put him in the Hall. Part of the issue with Lee Smith has always been the overrating of saves, and I am not surprised that he got in through the Today's Game Era Committee, given the many votes he got from writers over the years in the regular voting. So I can mostly understand his case. But Harold Baines? He was a very good player, but he really lowers the bar at his position. He never got a sniff from the writers, nor did he deserve it.

I'm looking forward to the regular ballot, which will get us Mariano Rivera (who may break the record for highest voting percentage), Edgar Martínez (finally!), Roy Halladay, and maybe (and hopefully!) Mike Mussina will make it. Those four all richly deserve enshrinement in the Hall of Fame.

Maybe Lee Smith's election will help Billy Wagner's case?

Friday, December 07, 2018

"'C' is for Cookie": Academic Evaluation Edition

Comment: "'C' is for cookie. That's good enough for me!"

Comment 2: Apparently, some of my what we did in mathematics in Somerville was an even better idea than I thought. ;)

(Tip of the cap to Jacquelyn Gill.)

Tuesday, December 04, 2018

Does Particle Man Hate Tariff Man?

Does Particle Man hate Tariff Man? And what about Triangle Man?

Jewelry and Differential Equations

I'm sure that many jewel thieves started on the road to crime after failed attempts to solve a differential equation.

Tales from the ArXiv: Laundering Anti-Money

This new paper has the following title: "Scalable Graph Learning for Anti-Money Laundering: A First Look"

Wow! I wonder what happens when laundered anti-money collides with laundered money?

Tuesday, November 27, 2018

Tales from the ArXiv: Grandma Got Run Over By a Reindeer

If I had done this study, I would make a video submission to the Gallery of Nonlinear Images (may it rest in peace), and I would set it to the tune of the song Grandma Got Run Over By a Reindeer. Just saying...

Extra Special Mathematics Terminology

Monday, November 26, 2018

"Motor Primitives in Space and Time via Targeted Gain Modulation in Cortical Networks"

Our paper officially came out in Nature Neuroscience today! Here are some details.

Title: Motor Primitives in Space and Time via Targeted Gain Modulation in Cortical Networks

Authors: Jake P. Stroud, Mason A. Porter, Guillaume Hennequin, and Tim P. Vogels

Abstract: Motor cortex (M1) exhibits a rich repertoire of neuronal activities to support the generation of complex movements. Although recent neuronal-network models capture many qualitative aspects of M1 dynamics, they can generate only a few distinct movements. Additionally, it is unclear how M1 efficiently controls movements over a wide range of shapes and speeds. We demonstrate that modulation of neuronal input–output gains in recurrent neuronal-network models with a fixed architecture can dramatically reorganize neuronal activity and thus downstream muscle outputs. Consistent with the observation of diffuse neuromodulatory projections to M1, a relatively small number of modulatory control units provide sufficient flexibility to adjust high-dimensional network activity using a simple reward-based learning rule. Furthermore, it is possible to assemble novel movements from previously learned primitives, and one can separately change movement speed while preserving movement shape. Our results provide a new perspective on the role of modulatory systems in controlling recurrent cortical activity.

Wednesday, November 21, 2018

Introduction to "Confusion Equations"

Proposal: "Convection–Diffusion Equations" should be called "Confusion Equations" (or at least "Conffusion Equations").

Tales from the ArXiv: Shit's About to Get Octonionic!

Here is an interesting-looking a new paper (by Michael Freedman, Modjtaba Shokrian-Zini, and Zhenghan Wang ) called "Quantum computing with Octonions".

One thing that I find really exciting in the last few years is seeing octonions show up more and more in (in-the-process-of-becoming) practical things!

"Shit's about to get octonionic!", as some of us might say. ;)

Tuesday, November 20, 2018

Adrián Beltré Announces Retirement

Adrián Beltré has announced his retirement. Next stop, Cooperstown!

I was hoping that Beltré would continue playing, as he's still very effective. Also, if he spent time playing as the oldest player in the Major Leagues, he would have become the first player ever to spend time as both the youngest player in the Majors and as the oldest one.

Sunday, November 18, 2018

A Useful Exercise for Junior Scholars on the Academic Job Market

Here is a story and useful exercise for people on the job market for junior faculty positions or postdocs: When I was a postdoc at Georgia Tech, I was asked to go through about 20 postdoc applications for my thoughts on them. This was for the Center for Nonlinear Science in the physics department. (They had already removed about half of the original set of applications, so these were ones that made the cut to still be considered.) I decided that I would try to do it in one hour. It actually took me about two, even while purposely trying to be very fast. Then, in addition to helping the Georgia Tech folks (which was a good thing to do), I asked myself what I noticed about the applications during that intentionally rushed time. I then used those insights to help me improve my application materials.

There are various ways to do such an exercise, and I suspect most people will be doing it without looking at submitted applications in the above way. Gather a set of postdocs in a sufficiently broad field (e.g., "applied mathematics" or even just "mathematics"), as it's a good part of the exercise to see how you evaluate people who are studying topics that are somewhat outside of your expertise. Make sure there is a strict time limit, as you want to see what you notice — both good and bad — about applications in that setting, as it's a realistic setting for how applications are evaluated when it counts. I think you'll pick up some good insights this way, and you can also give each other helpful advice to improve your application materials.

There are various things that we (= senior academics) talk about and give as advice all of the time, but it's good to really try it for yourself. Then you'll see what you notice — both good and bad — in the bundle of applications that you read really quickly.

And, importantly, good luck on your job hunts!

Incidentally, you can find my research statement, teaching statement, and LaTeX file (with drafts of various 'personalization' paragraphs) from my time on the job market, to get my first faculty position, over a decade ago on this Web page

Rubik's Poincaré Disk

Wow! This is so awesome!

Friday, November 16, 2018

Which 2-Digit Parent Mathematics Subject Classification Should I Pick as my Primary Classification?

Suppose that you are in the situation that I am in terms of Mathematics Subject Classification, as shown in my tweet below (each term corresponds to one of these), and you are now supposed to pick one of these as your primary classification on the job market. (Note that I am not on the job market, but there was a time long ago when I was a junior scientist and I was faced with this situation.) Which one would you pick?

Applied mathematicians face this all the time (though my own research portfolio is a particularly extreme case of MSC failure) on the job market in their job applications for postdoc and faculty positions in mathematics departments in the United States. They forced to submit the standard American Mathematical Society (AMS) cover sheet, and they are then categorized according to an ontology that fails them utterly. It is systematically unfair to applied mathematicians.

The MSC needs to be revamped.

"Layer Communities in Multiplex Networks"

The final coordinates of one of my papers finally appeared with its journal coordinates, although a published version was already available in August 2017. It just took a while for the full special issue in which it appeared to be published, so only now to do we have our volume, issue, and page numbers. This is my first publication in Journal of Statistical Physics.

Here are some other details:

Title: Layer Communities in Multiplex Networks

Authors: Ta-Chu Kao and Mason A. Porter

Abstract: Multiplex networks are a type of multilayer network in which entities are connected to each other via multiple types of connections. We propose a method, based on computing pairwise similarities between layers and then doing community detection, for grouping structurally similar layers in multiplex networks. We illustrate our approach using both synthetic and empirical networks, and we are able to find meaningful groups of layers in both cases. For example, we find that airlines that are based in similar geographic locations tend to be grouped together in a multiplex airline network and that related research areas in physics tend to be grouped together in a multiplex collaboration network.

Thursday, November 15, 2018

2018 Most Valuable Player Awards

There were also no surprises with Major League Baseball's 2018 Most Valuable Player Awards. Mookie Betts of the Red Sox won by a landslide in the American League (with Mike Trout finishing second yet again and continuing his historical run of MVP-caliber seasons), and Christian Yelich of the Brewers won by a landslide in the National League. I thought that Mookie Betts would be unanimous; he was ranked first on 28 of the 30 ballots. Yelich was ranked first on 29 of the 30 ballots.

Some of the rankings are available on this page. Complete point totals are available for the American League on this page and for the National League on this page.

"WHAT IS... a Multilayer Network"

My "WHAT IS..." article on multilayer networks just appeared in published form today in the December 2018 issue of Notices of the American Mathematical Society.

Armin Straub has taken it upon himself to post a comprehensive list of all "WHAT IS..." articles. Mine is the 149th such article.

Wednesday, November 14, 2018

2018 Cy Young Awards

the 2018 Major League Baseball Cy Young Awards were announced today, and there weren't any surprises: Jacob deGrom of the Mets ran away with the National League award, and Blake Snell of the Rays won a close race over Justin Verlander of the Astros.

Tuesday, November 13, 2018

2018 Major League Baseball Managers of the Year

The 2018 American League Manager of the Year is Bob Melvin of the Oakland Athletics. The 2018 National League Manager of the Year is Brian Snitker of the Atlanta Braves.

What Happens in Columbus Stays in Columbus

I'm off the Columbus, the only city in Ohio I've ever visited. I'll be at Ohio State again, though mainly visiting a different group than usual this time. I'm looking forward to chatting with their various data folks, as well as chatting with my collaborators. (There is a nonzero intersection in these groups.)

Monday, November 12, 2018

Ohtani and Acuña Jr. are the 2018 Rookies of the Year!

The Angels' Shohei Ohtani, who is both a position player and a pitcher, was the run-away winner of the American League Rookie of the Year Award. I knew he had a good chance, but I thought the balloting was going to be a tight three-way race between Ohtani, and Yankee infielders Miguel Andujar and Gleyber Torres. You can find the rankings and point totals on this page. In the National League, the balloting went as expected: the Braves' Ronald Acuña Jr. is the Rookie of the Year, Juan Soto of the Nationals finished second, and Walker Buehler of the Dodgers finished a distant third. (The final ranking and point totals are both available in the link above.)

The 2018 class of Major League Baseball rookies was very strong indeed!

Sunday, November 11, 2018

"Roll for Initiative"

(Well, "Roll for surprise." probably conveys the implication better, but it doesn't seem as good.)

Congratulations to Dr. Alejandro Martínez!

My doctoral student Alejandro Martínez has now officially finished his D.Phil. (i.e., Ph.D.), with a dissertation called Disordered Granular Crystals.

His thesis work includes several awesome papers, including this one, this one, this one, this one, and this one. (Alejandro also has additional papers from his thesis era that are in collaboration with other people.)

Alejandro is now a postdoctoral scholar in computational biology in Chile.

Monday, November 05, 2018

Plants that Look like Stones


Sometimes the Refereeing Process Actually Works :)

We had a paper just accepted to PRE, and I wanted to show it to someone who I thought may not have seen it.

Me: "Yes, we need to upload the revised version to the arXiv reasonably soon. We changed it substantially (we had a very thorough and helpful referee), so I didn't want to only point you to the old version."

Response: "I hesitated to tell you this in the first message, but I was the referee--thanks for the compliment, all the more meaningful since you didn't know!!"

As frustrating as this can all be (and it is very often indeed), sometimes the process really does work, and sometimes you end up accidentally complimenting somebody a lot instead of accidentally having egg on your face. ;)

Sunday, November 04, 2018

Tales from the ArXiv: The Power Law OF DEATH

First I saw a researcher (Geoff West) claim that there is The Power Law of DOOM! (That's my name for it — not theirs.) At some point, I thought I had that in a blog post, but now I think it was only verbal snarky remarks and a Facebook entry. It started with a talk that he gave years at Oxford in which Geoff started off by saying that he was only going to have very modest conclusions in his seminar, but by the end of the talk, he was predicting the imminent decline of civilization.

And on the heels of The Power Law OF DOOM, we now have claims of The Power Law OF DEATH in a new arXiv paper called "Statistical study of time intervals between murders for serial killers".

In both cases (and as is common), the claims of a power law are unlikely to be justified statistically.

See also The Small-World Network OF LUST, this old blog entry, and this old blog entry.

Wednesday, October 31, 2018

Why are Pencils Yellow?

Monday, October 29, 2018

E. L. Ince and the State of Differential Equations in England in 1926

Saturday, October 27, 2018

Dodgers Win Game 3 of the World Series 3–2 in 18 Innings!


It's a great day for a ball game. Let's play two!

Many records were set, including longest postseason game (by time) and longest World Series game (by both inning and time). It tied the record for most innings in a postseason game.

(We're still down 2 games to 1, so we have an uphill climb. But today was really exciting. Let's see what tomorrow brings!)

Monday, October 22, 2018

Spatial and Information Efficiency in Price Lists

Everything's clear, right?

(Tip of the cap to Heather Zinn Brooks.)

"Network Science In Education: Transformational Approaches in Teaching and Learning"

Our book on network science in education just came out. Here are some details.

Title: Network Science In Education: Transformational Approaches in Teaching and Learning

Editors: Catherine B. Cramer, Mason A. Porter, Hiroki Sayama, Lori Sheetz, and Stephen Miles Uzzo

The book also includes my chapter about developing my undergraduate mathematics course about networks.

Sunday, October 14, 2018

Which Headline Do You Prefer?

Using a 'Sort' Function to Order the Chicken and the Egg

(I saw this through a 'like' by Chris Danforth on Twitter.)

Friday, October 12, 2018

A Map of Every Building in America


A Really Fancy Visual Illusion


Thursday, October 04, 2018

Amazing Visual Illusion: A Dynamic Müller–Lyer Illusion

This visual illusion is amazing. It is a dynamic Müller–Lyer illusion.

(Tip of the cap to Marcel Salathe.)

Wednesday, October 03, 2018

Look at Me, I'm 𝞧 sub d...

I am going to have a field day for puns with this new (for me) nugget of information...

Tuesday, October 02, 2018

How Many First-Authored Papers in "Leading" Journals Does One Need to be Hired as an Assistant Professor?

This is in ecology, but we can think of analogous exercises for mathematics and physics (including also with numbers of citations of papers at the time of being hired).

FYI: I have seen several things on this blog over the years that are relevant far beyond their core ecology audience, so it's worth a look beyond this post.

Update: It's also not required to have lots of citations to get a top faculty job. It would be good to see a distribution of what people have had in practice. (The number of citations listed by Google Scholar for me for 2006 is 53.)

Monday, October 01, 2018

Dodgers Win 6th Straight National League West Division Title!

The Dodgers won the game-163 tie-breaker with the Colorado Rockies to win their 6th straight National League West division title!

We face the Atlanta Braves in one of the two National League Division Series starting on Thursday. Go Dodgers!

Monday, September 24, 2018

Will the Authors of this Paper Look Back in Anger?

Key question: Will the authors look back in anger when they read their referee reports on this paper?

Wednesday, September 19, 2018

Tuesday, September 18, 2018

Trying to Divide by 0 on a Mechanical Calculator


Monday, September 17, 2018

"Inferring Parameters of Prey Switching in a 1 Predator–2 Prey Plankton System with a Linear Preference Tradeoff"

Another of my papers came out in final published form today.

Title: Inferring Parameters of Prey Switching in a 1 Predator–2 Prey Plankton System with a Linear Preference Tradeoff

Authors: Sofia H. Piltz, Lauri Harhanen, Mason A. Porter, and Philip K. Maini

Abstract: We construct two ordinary-differential-equation models of a predator feeding adaptively on two prey types, and we evaluate the models’ ability to fit data on freshwater plankton. We model the predator’s switch from one prey to the other in two different ways: (i) smooth switching using a hyperbolic tangent function; and (ii) by incorporating a parameter that changes abruptly across the switching boundary as a system variable that is coupled to the population dynamics. We conduct linear stability analyses, use approximate Bayesian computation (ABC) combined with a population Monte Carlo (PMC) method to fit model parameters, and compare model results quantitatively to data for ciliate predators and their two algal prey groups collected from Lake Constance on the German–Swiss–Austrian border. We show that the two models fit the data well when the smooth transition is steep, supporting the simplifying assumption of a discontinuous prey-switching behavior for this scenario. We thus conclude that prey switching is a possible mechanistic explanation for the observed ciliate–algae dynamics in Lake Constance in spring, but that these data cannot distinguish between the details of prey switching that are encoded in these different models.

Note: This paper is actually the third in a series of papers that arose from Sofia's doctoral thesis. In all three, we studied prey switching in plankton as a dynamical system. However, although we were concerned in all three papers with the same ecological situation, we modeled it in three different mathematical ways: using piecewise-smooth dynamical systems (in paper 1), using fast–slow dynamical systems (in paper 2), and using smooth dynamical systems (in this paper). It is really important to model the same phenomenon in different ways and to compare the qualitative features of the different models against each other as well as to empirical data. I am really pleased with this effort, which Sofia did a superb job of leading.

"Frequency-Based Brain Networks: From a Multiplex Framework to a Full Multilayer Description"

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

Title: Frequency-Based Brain Networks: From a Multiplex Framework to a Full Multilayer Description

Authors: Javier M. Buldú and Mason A. Porter

Abstract: We explore how to study dynamical interactions between brain regions by using functional multilayer networks whose layers represent different frequency bands at which a brain operates. Specifically, we investigate the consequences of considering the brain as (i) a multilayer network, in which all brain regions can interact with each other at different frequency bands; and as (ii) a multiplex network, in which interactions between different frequency bands are allowed only within each brain region and not between them. We study the second-smallest eigenvalue λ2 of the combinatorial supra-Laplacian matrix of both the multiplex and multilayer networks, as λ2 has been used previously as an indicator of network synchronizability and as a biomarker for several brain diseases. We show that the heterogeneity of interlayer edge weights and, especially, the fraction of missing edges crucially modify the value of λ2, and we illustrate our results with both synthetic network models and real data obtained from resting-state magnetoencephalography. Our work highlights the differences between using a multiplex approach and a full multilayer approach when studying frequency-based multilayer brain networks.

Bonus: This paper has an easter egg. Can you find it? (Hint: This is Spinal Tap.)

Tuesday, September 11, 2018

A Very Exciting (and Dangerous?) Mathematics Conference

P.S. I wonder what they actually have in mind with that session? I'm at a loss. I suppose it's clearer to the people who are actually attending the conference?

Tuesday, September 04, 2018

Referee Reports for the Watts–Strogatz 'Small World' Paper

This is a great document!

Steve Strogatz posted his referee reports (with annotations for their revision plans) about his genre-defining 1998 ‘small world’ paper with Duncan Watts.

It just goes to show that misguided, skeptical reports (see Referee 2 in the upper right) happen to the best of us.

Referee 2 was confused about the implications of the work to systems other than those studied (and possibly even to those applications)…

(The source is Steve's tweet. I posted the picture separately to orient it correctly.)

Monday, September 03, 2018

Googly Eyes, and Freshness of Fish

Well, this story is fishy. Wow. (And oy vey.)

The headline pretty much sums it up: Store shut down after owners caught sticking googly eyes on fish to look fresher

P.S. There are also other uses for googly eyes.

(Tip of the cap to Renée O'Rear Handley.)

Hindsight's 2020 Presidential Campaign

I don't know about you, but I'll be voting for the team of Hindsight/Forethought in 2020.

Saturday, September 01, 2018

What Happens in Sydney Stays in Sydney

I am at LAX for my trip Down Under!

The only previous time I was in Australia was in 2005 for my interview at University of Sydney. (I am visiting a collaborator at Macquarie University, and I'll be giving one teach each there and at University of Sydney.)

"Isomorphisms in Multilayer Networks"

This paper first appeared on the arXiv in 2015 and was published in advanced access about a year ago. It finally has its final volume and page coordinates, so I am finally writing a blog entry about. At this stage, the paper certainly doesn't feel "new" anymore, but it has some useful ideas in it, and it's also my first paper in an IEEE journal. This paper is also rather unusual for me, in that my coauthor Mikko Kivelä and I decided that the clearest way to present things would be to write the paper in definition–theorem–proof format. I almost never write papers that way. Anyway, here are a few details.

Title: Isomorphisms in Multilayer Networks

Authors: Mikko Kivelä and Mason A. Porter

Abstract: We extend the concept of graph isomorphisms to multilayer networks with any number of “aspects” (i.e., types of layering). In developing this generalization, we identify multiple types of isomorphisms. For example, in multilayer networks with a single aspect, permuting vertex labels, layer labels, and both vertex labels and layer labels each yield different isomorphism relations between multilayer networks. Multilayer network isomorphisms lead naturally to defining isomorphisms in any of the numerous types of networks that can be represented as a multilayer network, and we thereby obtain isomorphisms for multiplex networks, temporal networks, networks with both of these features, and more. We reduce each of the multilayer network isomorphism problems to a graph isomorphism problem, where the size of the graph isomorphism problem grows linearly with the size of the multilayer network isomorphism problem. One can thus use software that has been developed to solve graph isomorphism problems as a practical means for solving multilayer network isomorphism problems. Our theory lays a foundation for extending many network analysis methods—including motifs, graphlets, structural roles, and network alignment—to any multilayer network.

Friday, August 31, 2018

The Winning Game and a Potentially Interesting Dodger Factoid

In franchise history, the Dodgers have never had a season in which none of their pitchers has won 10+ games.

This year, our win leader is Ross Stripling (with 8 wins), who is currently on the disabled list.

We have a good chance to make the playoffs, and there is an even better chance that none of our pitchers will get double digits in wins. "Accomplishing" both of these things in the same season is not easy.

(I found this out from Charley Steiner on tonight's broadcast.)

Thursday, August 30, 2018

"Do Complex-Systems Scientists Dream of Emergent Sheep?"

I came up with this title earlier today, and I need to write an article (or book or something) with this title.

Update: And, to complete the picture, note that there is also an old game called Netrunner.

Carpeting Dragon*Con

The old carpet at the Atlanta Marriott — which unfortunately was replaced with something much more boring — has become a big part of the legend of Dragon*Con. (It also appeals to me mathematically, of course.)

Many Dragon*Con costumes and related things still invoke the old carpet.

Here is an article (to which I can't get full access) that appears to be about carpet-related costumes more generally (though the front picture is one from Dragon*Con).

Wednesday, August 29, 2018

Scientific Journals are for Kids!

The journal Frontiers for Young Minds is very cool!

It is "an open-access scientific journal written by scientists and reviewed by a board of kids and teens."

Here is some text from their online blurb:

That is why distinguished scientists are invited to write about their cutting-edge discoveries in a language that is accessible for young readers, and it is then up to the kids themselves – with the help of a science mentor – to provide feedback and explain to the authors how to best improve the articles before publication.

As a result, Frontiers for Young Minds provides a collection of freely available scientific articles by distinguished scientists that are shaped for younger audiences by the input of their own young peers.

I approve!

(Tip of the cap to Petter Holme.)

Tuesday, August 28, 2018

Advice to Students: "Think for Yourself."

This statement gives excellent advice! In fact, it's the main thing that I try to convey to students.

"We are scholars and teachers at Princeton, Harvard, Yale, and other institutions who have some thoughts to share and advice to offer students across the country. Our advice can be distilled to three words:

Think for yourself."

The full statement, which I signed, is worth reading.

Monday, August 27, 2018

The Karate Club Will Long Live in Network-Science Infamy

Especially with the new Karate Club lore that has made it into the 2nd edition of Mark Newman's textbook.

(However, Mark misspelled "awesome" as "dubious", for some reason.)

P.S. You can see the history of the ZKCC at this website and buy ZKC memorabilia at The Power Law Shop.

Friday, August 17, 2018

Infinite Loop

(Tip of the cap to Manlio De Domenico.)

Tuesday, August 14, 2018

What Happens at WorldCon 76 Stays at WorldCon 76

I am at the airport — experiencing a lovely 2.5-hour delay in my flight — and will be flying to San Jose, California to attend this year's WorldCon. Several of my friends will be there, so it should be lots of fun.

I am looking forward to geeking out!

(I am also looking forward to getting out of this crowded, shitty airport. LAX is awful.)

Monday, August 13, 2018

A Wassermanian–Faustian Bargain

Friday, August 10, 2018

"Network Analysis of Particles and Grains"

Our review article on granular and particulate networks, which appeared in advanced access a few months ago, is now out in final form (with its page numbers and other coordinates). Here are some details.

Title: Network Analysis of Particles and Grains

Authors: Lia Papadopoulos, Mason A. Porter, Karen E. Daniels, and Danielle S. Bassett

Abstract: The arrangements of particles and forces in granular materials have a complex organization on multiple spatial scales that range from local structures to mesoscale and system-wide ones. This multiscale organization can affect how a material responds or reconfigures when exposed to external perturbations or loading. The theoretical study of particle-level, force-chain, domain and bulk properties requires the development and application of appropriate physical, mathematical, statistical and computational frameworks. Traditionally, granular materials have been investigated using particulate or continuum models, each of which tends to be implicitly agnostic to multiscale organization. Recently, tools from network science have emerged as powerful approaches for probing and characterizing heterogeneous architectures across different scales in complex systems, and a diverse set of methods have yielded fascinating insights into granular materials. In this article, we review work on network-based approaches to studying granular matter and explore the potential of such frameworks to provide a useful description of these systems and to enhance understanding of their underlying physics. We also outline a few open questions and highlight particularly promising future directions in the analysis and design of granular matter and other kinds of material networks.

Thursday, August 09, 2018

A Touching Song about a Matrix Entry that is not Well-Defined

This is a touching song about a matrix entry that is very sad because it is not well-defined.

Monday, August 06, 2018

Workshop on Evidence-Based Diversity Initiatives

I hope that some of my mathematics, networks, and complex-systems peeps attend this workshop! It looks good.

(P.S. Jess Wade has been doing amazing things in her prolific writing of Wikipedia entries.)

Saturday, August 04, 2018

What Happens in San José (Costa Rica) Stays in San José (Costa Rica)

I am heading off to Costa Rica for a visit related to an epidemiology project related to combatting Dengue Fever, Zika, and Chikungunya using mathematical modeling and network analysis.

Thursday, August 02, 2018

An Author Named "Tapas Bar"

The first author of this new paper is named "Tapas Bar".

Suddenly, I feel hungry.

Our Physics Today Obituary of Norman Zabusky

David Campbell, Alan Newell, and I wrote an obituary of Norman Zabusky for Physics Today. It just came out.

Previously, we wrote an obituary of Zabusky for DSWeb.

Wednesday, August 01, 2018

2018 Fields Medals

The 2018 Fields Medals in mathematics have been announced!

You can also read short prize citations for the four Fields Medalists and the Nevanlinna Prize (in theoretical computer science).

Tuesday, July 31, 2018

"Topological Data Analysis of Continuum Percolation with Disks"

One of my papers came out in final form today. Here are some details and a story.

Title: Topological Data Analysis of Continuum Percolation with Disks

Authors: Leo Speidel, Heather A. Harrington, S. Jonathan Chapman, and Mason A. Porter

Abstract: We study continuum percolation with disks, a variant of continuum percolation in two-dimensional Euclidean space, by applying tools from topological data analysis. We interpret each realization of continuum percolation with disks as a topological subspace of [0,1]^2 and investigate its topological features across many realizations. Specifically, we apply persistent homology to investigate topological changes as we vary the number and radius of disks, and we observe evidence that the longest persisting invariant is born at or near the percolation transition.

And to give a story, or at least the hint of the interesting relationship that I sometimes have with typesetters and editors, here is a note that I received from them while we were working on the galley proofs.

Update (8/05/18): A nice way of phrasing things is that we're in a nonassociative situation, and hyphens are a great tool to indicate exactly (and tersely) where the parentheses should be to group terms in a way that renders their meaning unambiguous. (And, naturally, if somebody makes a change in my text that I don't like, my immediate desire is to change it back.)

Monday, July 30, 2018

A Cartoon Depiction of Deep Learning Versus Traditional Machine Learning

So true. :)

(Tip of the cap to Michael Stumpf.)

The Paradox of PLOS One and Scientific Reports

Whenever I see somebody bragging about getting a paper published by a trashy journal like PLOS One or Scientific Reports, I inevitably wonder whether they're being serious (but naive) or whether they're trolling people. Seriously, I can't tell.

Also, remember the mantra: FIPO (= "Fuck it. PLOS One.")

Sunday, July 29, 2018

Tales from the ArXiv: "Blueberry Earth"

I am amused. :)

(However, I do wish that the author had used the subjunctive in the 'what if' question.)

Update: Here is the first paragraph of the Summary: So, to sum up, to a person standing on the surface of the Earth when it turns into blueberries, the first effect would be a drastic reduction of gravity. Standing on the blueberries might be possible in theory, except that almost immediately they begin to compress rapidly and air starts erupting everywhere. The effect is basically the worst earthquake ever, and it keeps on going until everything has fallen 715 km. While this is going on everything heats up drastically until the entire environment is boiling jam and steam. The end result is a world that has a steam atmosphere covering an ocean of jam on top of warm blueberry granita.

Saturday, July 28, 2018

Complex Variables and the Meaning of 𝛏

This tweet speaks the truth!

Two remarks:

(1) One of the main purposes of taking complex analysis is learning how to properly write Greek letters.

(2) I specifically practiced how to draw \xi when I took complex analysis.

(Tip of the cap to Dave Richeson.)

Smurfy Peer Review

Resolved: I am going to start taking inspiration from The Smurfs when I write referee reports for articles that particularly annoy me.

To wit:

"Where did the authors smurf up this idea?"

"This figure is smurfed."

"The authors might want to consider smurfing the abstract a little bit more."

Update: I know; I know: this isn't very smurfy of me.

Update 2: "A total smurf job."

Tuesday, July 24, 2018

Tales from the ArXiv: Low and High Mason Numbers

Here is a new paper on the ArXiv.

Here is a quote from the abstract: In the limit of low Mason number, the dynamical system admits a periodic solution in which the magnetic moment of the swimmer tends to align with the magnetic field. In the limit of large Mason number, the magnetic moment tends to align with the average magnetic field, which is parallel to the axis of rotation.

I operate in the limit of low Mason number, and I claim that this limit is singular.

Monday, July 23, 2018

Opinion: "Are Theoretical Results 'Results'?"

I agree strongly with Ray Goldstein: YES!!!!!!

Moreover: Hell yes!

This is a major issue for interdisciplinary students and postdocs (and more senior scholars), and this is a very helpful paper for them to read as they navigate these waters. I also really like the fact that Ray included two different versions of a 'Results' section in his opinion article.

"Quasiperiodic Granular Chains and Hofstadter Butterflies"

Our article just came out in final form today. It provides the cover picture of an issue of Philosophical Transactions of the Royal Society A. Here are some details.

Title: Quasiperiodic Granular Chains and Hofstadter Butterflies

Authors: Alejandro J. Martínez, Mason A. Porter, and Panayotis G. Kevrekidis

Abstract: We study quasiperiodicity-induced localization of waves in strongly precompressed granular chains. We propose three different set-ups, inspired by the Aubry–André (AA) model, of quasiperiodic chains; and we use these models to compare the effects of on-site and off-site quasiperiodicity in nonlinear lattices. When there is purely on-site quasiperiodicity, which we implement in two different ways, we show for a chain of spherical particles that there is a localization transition (as in the original AA model). However, we observe no localization transition in a chain of cylindrical particles in which we incorporate quasiperiodicity in the distribution of contact angles between adjacent cylinders by making the angle periodicity incommensurate with that of the chain. For each of our three models, we compute the Hofstadter spectrum and the associated Minkowski–Bouligand fractal dimension, and we demonstrate that the fractal dimension decreases as one approaches the localization transition (when it exists). We also show, using the chain of cylinders as an example, how to recover the Hofstadter spectrum from the system dynamics. Finally, in a suite of numerical computations, we demonstrate localization and also that there exist regimes of ballistic, superdiffusive, diffusive and subdiffusive transport. Our models provide a flexible set of systems to study quasiperiodicity-induced analogues of Anderson phenomena in granular chains that one can tune controllably from weakly to strongly nonlinear regimes.

This article is part of the theme issue ‘Nonlinear energy transfer in dynamical and acoustical systems’.

Sunday, July 22, 2018

I Would Code Anything for Love (but I Won't Code That)

Somebody clearly wants an Ig Nobel... Wow.

(Also, I am highly amused!)

Money quote from the programming language's GitHub page:

"Rockstar is a dynamically typed Turing-complete programming language.

Rockstar is designed for creating computer programs that are also song lyrics, and is heavily influenced by the lyrical conventions of 1980s hard rock and power ballads."

Update (7/23/18): I wrote a blurb about Rockstar for the Improbable Research blog.

Saturday, July 21, 2018

Scientific Nomenclature: The "Thagomizer"

This is so awesome!

(Tip of the cap to C E Watkins.)

"Smooths" Versus "Smoothes"

A new champion was crowned recently.

Update: Also, this may be Microsoft's fault.

Friday, July 20, 2018

Proof of Existence of Sunlight in England

At least it was a book that was published in The Other Place. ;)

Thursday, July 19, 2018

A Buzzcock Conjecture

Just give me an excuse to make music-lyric (or certain other pop culture) jokes — any excuse at all.

You can also take a look on Twitter.

Wednesday, July 18, 2018

Tales from the ArXiv: Don't Feed Random Walkers After Midnight

There is a new paper on arXiv about reactive random walkers.

Quoting from the abstract: "The model is highly versatile, as the motion of the walkers can be fed on topological properties of the nodes..."

Comment: But don't feed them after midnight.

Dodgers Trade for Manny Machado!

It's now official (after some increasingly hot rumors, especially yesterday at the All-Star Game): The Dodgers have traded for Manny Machado, the biggest ticket on this season's trade market. Hell yes!!!!

With Corey Seager out for the year, having Machado to play shortstop the rest of the year is most excellent indeed!

Tuesday, July 17, 2018

Medieval Fantasy City Generator

This is so cool!

I also wonder if it uses any generative-model ideas from urban analytics and/or complex systems?

(Tip of the cap to Dungeons and Dragons Memes.)

Monday, July 16, 2018

Heart and Caffeine Plushies

I bought Heart a couple of months ago, and Caffeine just arrived today.

"Message-Passing Methods for Complex Contagions"

Here is the published version of a the chapter that James Gleeson and I wrote for the book Complex Spreading Phenomena in Social Systems, which was edited by Sune Lehmann and YY Ahn. You can also find preprint versions of many chapters available for free on this website.

XKCD: "Negative Results"

I am amused.

Friday, July 13, 2018

Creating Wikipedia Entries for Underrepresented Scientists and Engineers

As described in this article, physicist Jess Wade has been doing incredible work on writing new Wikipedia entries.

Wednesday, July 11, 2018


If I recall correctly, I encountered this one when purchasing theatre tickets at a certain venue in Oxford.

Real-Life Elliptical Billiard Table

I approve!

Now we just need real-life Sinai and stadium billiards (and, of course, a mushroom billiard, to make Lyonia happy).

(Tip of the cap to Alex Bellos.)

Update: The table pictured in the article appears to be a circle, rather than a more general ellipse.

Algorithmic Author Ordership

I am amused. :)

Tuesday, July 10, 2018

Awesome Close-Up Photos of Snails

You can snail, you can snail...

(Tip of the cap to Invisible Scientist.)

Thursday, July 05, 2018

My Eponymous Agent-Based-Model (ABM) Simulator

(Tip of the cap to Sang Hoon Lee.)

Tuesday, July 03, 2018

"My" Eponymous Band

As some of you know, there is a band called Mason Porter. We both show up near the top of Google search for "Mason Porter" (and similar items). Over the years, I have been tagged on several Twitter posts instead of them. I am also followed by a few random people who are interested in folk and bluegrass music, and I have even had some good-natured Twitter battles with the band when I visit Philadelphia.

And now, on this occasion, even the band itself accidentally tagged me in their Facebook post instead of themselves!

Rock on! ("Folk on?")

One of these years, I seriously need to crash one of their shows with a short mathematics lecture.

Monday, July 02, 2018

"International Conference on Newfangled Methods"


Sunday, July 01, 2018

What Happens in Newcastle Stays in Newcastle (2018 Edition)

I've been visiting friends in Newcastle the last couple of days.

Thursday, June 28, 2018

RIP Harlan Ellison (1934–2018)

The great writer Harlan Ellison (who contributed much to science fiction, as well as other genres) died today.

Here is a picture with him at Dragon*Con in 2003. He complimented me on the shirt I was wearing, and rolled his eyes to signal to me (while I was waiting patiently at the front of the line) that the person in front of me in line for his autograph (who gave him tons and tons of things to sign) was an idiot. For me, he signed a well-read copy of the 35-year retrospective of his work, and he agreed to be in the picture below. Unlike recent Dragon*Cons, Ellison's autograph was free. He seemed to appreciate the fact that I had obviously read the book that I asked him to sign.

Update: Here is an obituary from The Nerdist.

Tuesday, June 26, 2018

Another Living Network

Here is another living network, as one can see especially prominently in the right panel.

Other examples of living networks are fungal networks.

(Tip of the cap to Jessica Rosenkrantz.)

Monday, June 25, 2018

"Detecting Sarcasm with Deep Convolutional Neural Networks"

I think they found it.

(Tip of the cap to Peter Rothman.)

Sunday, June 24, 2018

Yet Another Amazing Tiling from Tiling Bot

Tiling Bot has been producing lots of amazing (and often gorgeous) tilings on Twitter. Today's is one of my favorites.

I strongly recommend looking through Tiling Bot's feed.

Saturday, June 23, 2018

What Happens in Oxford Stays in Oxford

I arrived in Oxford last Sunday and will be here for a while, staying in Somerville and hanging out with my peeps (including some of my former students) from College as well as the Mathematical Institute. It's great to still be part of the extended family!

I'll also be participating and speaking at Howison-fest, a workshop in honor of Sam Howison's 60th birthday.

Thursday, June 21, 2018

"FU" Stands for "Fundamental Unit"

Naturally, when I see "FU", the first term that comes to mind is "fundamental unit".

Remember: "FUs are biologically well defined".

This screenshot is from this new paper.

(Tip of the cap to Alex Vespignani.)

Ground Control to Major Tom: Perfect Photographic Timing

I approve!

Wednesday, June 20, 2018

Poincaré Disk: Fantasy Edition

I love it!

A Bulging Visual Illusion

This is a great visual illusion!

(Tip of the cap to Ben Orlin.)

Scholarship: Part of the Scientific Reward System

I may have been slightly snarky. :)

Tuesday, June 19, 2018

Apple Seismology

Here is a cool 'Quick Study' about "apple seismology".

Quoting the article's lead: Just as an earthquake’s seismic waves reveal properties of Earth’s interior, elastic surface waves on an apple can tell us about what’s going on inside the fruit.

This research may be a contender for an Ig Nobel prize.

Update: Apple seismology was discussed originally in a 1973 mathematical modeling paper by J.R. Cooke and Richard Rand. (This paper is cited in the Physics Today article above.)

An Alternative to a Faculty Retreat

Instead of having a Faculty Retreat, why don't we have a Faculty Victory this time?


Hitting a Major League Home Run Before One's First Major League Home Run

"Yesterday's" home run by Juan Soto, in a game that was suspended May 15th and completed yesterday, will be part of a great trivia question in the future.

Quoting from the article to which I linked:

On Monday, the Washington Nationals rookie crushed a tiebreaking, pinch-hit, two-run homer against the New York Yankees in the continuation of a game that started May 15 — five days before his big league debut.

According to the Elias Sports Bureau, Soto's blast will not be considered his first major league homer, but it will be counted as a home run hit on May 15.

Saturday, June 16, 2018

"Female Drosophila melanogaster Respond to Song-Amplitude Modulations"

One of my papers came out in final published form a few days ago. Here are some details. (Also see the paper's supplementary material for an interview with the first author, my former D.Phil. student Birgit Brüggemeier.)

Title: Female Drosophila melanogaster Respond to Song-Amplitude Modulations

Authors: Birgit Brüggemeier, Mason A. Porter, Jim O. Vigoreaux,and Stephen F. Goodwin

Abstract: Males in numerous animal species use mating songs to attract females and intimidate competitors. We demonstrate that modulations in song amplitude are behaviourally relevant in the fruit fly Drosophila. We show that Drosophila melanogaster females prefer amplitude modulations that are typical of melanogaster song over other modulations, which suggests that amplitude modulations are processed auditorily by D. melanogaster. Our work demonstrates that receivers can decode messages in amplitude modulations, complementing the recent finding that male flies actively control song amplitude. To describe amplitude modulations, we propose the concept of song amplitude structure (SAS) and discuss similarities and differences to amplitude modulation with distance (AMD).

Thursday, June 14, 2018

Adrián Beltré Now has More Hits than All Other Non-US-Born Players

Adrián Beltré now has more MLB hits than any other non-US-born player who ever played the game!

He passed Ichiro in the game that ended a few hours ago.

Saturday, June 09, 2018

What Happens in Paris Stays in Paris

I am at the airport. I'll be heading to Paris for NetSci 2018!

Sunday, June 03, 2018

Excellent Notation for Predator–Prey Dynamics

I approve!

(Tip of the cap to Karen Daniels.)

Triumphant Return of The Power Law Shop

Saturday, June 02, 2018

Jack and Jill had Issues

Mathematics is an Experimental Science


(Tip of the cap to Steve Strogatz.)

Friday, June 01, 2018

A Brief Celebration of #NationalDonutDay

Thursday, May 31, 2018

Tales from the ArXiv: "Calculating Spherical Harmonics Without Derivatives"

There is a new paper on the arXiv that apparently includes a new way of calculating spherical harmonics.

A part that some of you may find interesting is the pedagogical discussion at the beginning of Section 5, which starts: "Historically, there are five ways that spherical harmonics can be derived."

The one that is easiest (by far) for me to understand is the oldest method, which is by solving the differential equation. But I am mathematically inclined, and people with more physical intuition may prefer other methods.

(People who are more comfortable than I am with Lie manipulations may also prefer other approaches.)

Anyway, I appreciate the discussion in this paper.

Sunday, May 27, 2018

"Can Multilayer Networks Advance Animal Behavior Research?"

The final version of a new paper of mine now has its final coordinates in a journal. Here are some details.

Title: Can Multilayer Networks Advance Animal Behavior Research?

Authors: Matthew J. Silk, Kelly R. Finn, Mason A. Porter, and Noa Pinter-Wollman

Abstract: Interactions among individual animals — and between these individuals and their environment — yield complex, multifaceted systems. The development of multilayer network analysis offers a promising new approach for studying animal social behavior and its relation to eco-evolutionary dynamics.

Thursday, May 24, 2018

Innovative Pitching Usage: Micro-Starts by Relievers

The Rays started playing around with an interesting innovation in their pitcher usage in a recent series against the Angels: They started a reliever for one inning to face the tough top of their lineup, and then they brought in their scheduled "starter" for the second inning.

The Rays are doing this again in their upcoming series against the Orioles.

I think there is a lot of traction for more of this, though it will depend on a team's rotation (e.g., if you have one like the Astros, this is probably not as helpful as for the Rays), player, player egos, and so on.

Thursday, May 17, 2018

"The Pole Arm of Archaeology" and Other Epic Scholar Visualizations

Dan Hicks posted some epically bad scholar visualizations as a Twitter thread. My favorite one is The Pole Arm of Archaeology, which is about as epic as it sounds. ;)

(Tip of the cap to Brian Cox.)

Tuesday, May 15, 2018

'Working Paper' in Collaboration with International Monetary Fund: "Evolution of the Global Financial Network and Contagion: A New Approach"

A 'working paper' from a collaboration with folks from the International Monetary Fund (IMF) came out today. You can download it from this website. We also hope to submit a version of this work to a journal for publication. Here are some details.

Title: Evolution of the Global Financial Network and Contagion: A New Approach

Authors: Yevgeniya Korniyenko, Manasa Patnam, Rita Maria del Rio-Chanon, and Mason A. Porter

Abstract: This paper studies the interconnectedness of the global financial system and its susceptibility to shocks. A novel multilayer network framework is applied to link debt and equity exposures across countries. Use of this approach—that examines simultaneously multiple channels of transmission and their important higher order effects—shows that ignoring the heterogeneity of financial exposures, and simply aggregating all claims, as often done in other studies, can underestimate the extent and effects of financial contagion.The structure of the global financial network has changed since the global financial crisis, impacted by European bank’s deleveraging and higher corporate debt issuance. Still, we find that the structure of the system and contagion remain similar in that network is highly susceptible to shocks from central countries and those with large financial systems (e.g., the USA and the UK). While, individual European countries (excluding the UK) have relatively low impact on shock propagation, the network is highly susceptible to the shocks from the entire euro area. Another important development is the rising role of the Asian countries and the noticeable increase in network susceptibility to shocks from China and Hong Kong SAR economies.

Compilation of "Awesome" #BadStockPhotosOfMyJob

These stock photos of jobs (with much focus on scientific ones) are indeed hilariously bad.

Mathematics and physics get the familiar, cheesy writing-in-the-mirror treatment in some of these.

(Tip of the cap to Justin Howell.)

Fun Fact: My First Publication was a Dungeons & Dragons Character!

Saturday, May 12, 2018

You Wouldn't Like These Functions When They're Angry

There is a family of special functions called Anger functions. You wouldn't like them when they're angry.

Here is the context: Physics Today has agreed to publish an obituary for Norman Zabusky, so I needed to find some information that they require to be part of it. This led me to Norman's PhD thesis, which I found online. It briefly mentions something called Lommel polynomials, with which I wasn't familiar. The definition in a thesis appendix was terse — it's not exactly an important part of the thesis — so I looked at Wikipedia, and I kept seeing links to special functions that weren't familiar to me, and I have followed a couple of them. Anger functions are one family.

These various special functions are closely related to Bessel functions.

Thursday, May 10, 2018

Meaningless Connections and Empty Entities

And I spend lots and lots of time studying these things, including in the context of applications like social media. ;)

(Tip of the cap to Jane Shevtsov.)