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.)

Wednesday, May 09, 2018

The Pulse of Manhattan


Taking the First Stab at "Taking the First Stab"

I couldn't find this with a simple Google search, but if you think about it, the origin of the phrase "take the first stab" has to be rather violent.

Maybe a nice piece of art to go with somebody starting to write the initial draft of an academic paper would be a picture of a scientist quite literally taking an initial stab through a pile or papers or perhaps through a laptop.

(If anybody has a favored website for etymology and similar matters, please let me know. I was hoping my global search would turn up a good answer on one of those pages.)

And, by all means, somebody should take the first stab at answering my query.

Video of my Tutorial in Paper-Writing in Applied Mathematics

Here is a video of my recent (4/20) tutorial on paper-writing in applied mathematics.

You can also download the slides.

I hope that people find it helpful!

Tuesday, May 08, 2018

Important Paper on Seussian Configurations of Random-Graph Models

In network science, it is with very good reason that one should speak of "a" configuration model rather than "the" configuration model. To see an excellent discussion of this and related issues, be sure to go through this paper by Bailey Fosdick, Daniel Larremore, Joel Nishimura, and Johan Ugander.

Title: Configuring Random Graph Models with Fixed Degree Sequences

Authors: Bailey K. Fosdick, Daniel B. Larremore, Joel Nishimura, and Johan Ugander

In 2014, Aaron Clauset, David Kempe, and I (with help from Dan Larremore) organized a Mathematics Research Community in Network Science.

In addition to creating a network of network scientists from diverse backgrounds, some work was started there, and today the published version of what is in my opinion an extremely important paper has come out in final form in SIAM Review's 'Research Spotlights' section. I am, of course, talking about the aforementioned paper.

I'm very happy indeed for such excellent work to arise from this.

Congratulations to authors Bailey Fosdick, Daniel Larremore, Joel Nishimura, and Johan Ugander for creating this awesome paper!

I am posting this with an absolutely lovely Seussian picture from an arXiv version of the paper. This picture doesn't appear to have made the cut for the published piece. In addition to its wit and whimsy, a really great thing about the picture and its accompanying verse is that it also encodes the main message of the paper.

Note: I am on the editorial board of the Research Spotlights section of SIAM Review, but I had nothing whatsoever to do with the handling of this paper.

Friday, May 04, 2018

Albert Pujols gets his 3000th Career Hit!

Albert Pujols collected his 3000th career hit tonight, becoming the 32nd member of the club. He is one of four Major Leaguers with at least 600 homeruns and at least 3000 hits.

Thursday, May 03, 2018

Awesome Google Doodle

The new Google Doodle, which celebrates Georges Méliès, is really, really cool. Go interact with it!

Tuesday, May 01, 2018

Our Memorial Article for Norman J. Zabusky (1929–2018)

Along with David Campbell and Alan Newell, I have written a memorial article for my collaborator Norman Zabusky, who died in February. It was posted online earlier today.

Sunday, April 29, 2018

Crib Notes on a Fingernail (with \latex Notation)

If I were going to put mathematical formulas on my fingernail as crib notes, I'd also use \latex notation. :)

My favorite is the use of " \; ", which would allow the cheating student being modeled by the picture to ensure legible symbol spacing when writing exam solutions.

Saturday, April 28, 2018

Number of Spaces and Periods

Let the debating commence.

Tuesday, April 24, 2018

Balloon Skeleton Animals

These are amazing!

Monday, April 23, 2018

"Nanoptera in a Period-2 Toda Chain"

One of my papers recently came out in final form (with its volume and all of its other publication coordinates). Here are some details.

Title: Nanoptera in a Period-2 Toda Chain

Authors: Christopher J. Lustri and Mason A. Porter

Abstract: We study asymptotic solutions to a singularly perturbed, period-2 Toda lattice and use exponential asymptotics to examine "nanoptera," which are nonlocal solitary waves with constant-amplitude, exponentially small wave trains. With this approach, we isolate the exponentially small, constant-amplitude waves, and we elucidate the dynamics of these waves in terms of the Stokes phenomenon. We fi nd a simple asymptotic expression for these waves, and we study con figurations in which these waves vanish, producing localized solitary-wave solutions. In the limit of small mass ratio between the two types of particles in the lattice, we derive a simple antiresonance condition for the manifestation of such solutions.

Thursday, April 19, 2018

Manifolds Lying in a Higher-Dimensional Space

We often view manifolds as lying in some higher-dimensional space, but shouldn't we also consider ones that are telling the truth? 🤔

Tuesday, April 17, 2018

Tales from the ArXiv: "26 pages and 10 gorgeous figures"

The authors of this paper, in the comments field, advertised their paper as having "26 pages and 10 gorgeous figures".

They’re not bad. I wouldn’t call them gorgeous, though.

Resistance is for the Birds

Damn right. #resist

Sunday, April 15, 2018

Shopping for Groceries and Solving the Reimann Hypothesis

I love it!

Monday, April 09, 2018

Awesome Journal Idea: Young-Researcher, First-Author Interviews for Accepted Papers

Today, one of my papers was accepted by Biology Open, with which I didn't previously have any experience.

As part of their correspondence today, they also let the first author (my former doctoral student) know about the option of a young-scientist, first-author spotlight. They wrote the following (which you can also find on their website):

Congratulations on acceptance of your article in Biology Open. To help early-career researchers promote themselves alongside their papers, we have launched a series of interviews with the first authors of a selection of papers published in BiO. If you would like to be included in this interview series, please tell us more about yourself by answering the questions below. You can answer all or just some of the questions, and you may also suggest additional questions and provide your answers to them if you wish.

How interesting! I have never seen a journal do this before. What a great idea! We really need to do something like this in the mathematics and physics communities.

Here are their suggested questions:

What is your scientific background and the general focus of your lab?

How would you explain the main findings of your paper to non-scientific family and friends?

What are the potential implications of these results for your field of research?

What has surprised you the most while conducting your research?

What, in your opinion, are some of the greatest achievements in your field and how has this influenced your research?

What changes do you think could improve the professional lives of early career scientists?

What's next for you?

They then added the following:

So that we can create a short biography to accompany your interview, please ensure that you include your job title, the name of the Principal Investigator of your lab, your contact address and a one-line synopsis of your research interests. Include your Twitter handle, if you have one, so we can tag you in any related tweets.

They also asked for a picture of the first author and "a particularly striking, interesting or unusual image" from their research (along with a caption describing it).

Thursday, April 05, 2018

Tales from the ArXiv: Centenary of Emmy Noether's Invariante Variationsprobleme

This article commemorates the centenary of Emmy Noether's article Invariante Variationsprobleme.

Title: On the Wonderfulness of Noether's Theorems, 100 Years Later, and Routh Reduction

Author: Raphaël Leone

Abstract: This paper is written in honour of the centenary of Emmy Amalie Noether's famous article entitled Invariante Variationsprobleme. It firstly aims to give an exposition of what we believe to be the most significant and elegant issues regarding her theorems, through the lens of classical mechanics. Despite the limitation to this field, we try to illustrate the key ideas of her work in a rather complete and pedagogical manner which, we hope, presents some original aspects. The notion of symmetry coming naturally with the idea of simplification, the last part is devoted to the interplay between Noether point symmetries and the reduction procedure introduced by Edward John Routh in 1877.

Sunday, April 01, 2018

XKCD: "Right Click"

The new XKCD is another one of those that needs to be mapped out. I'm looking forward to seeing the resulting network. We should calculate some properties of it. :)

While navigating the menus, I managed to get eaten by a grue.

There are errors in some of the D & D categorizations.

Some April Fool's Day Stuff

I'll try to keep a running tab of some of the April Fool's Day stuff I notice. As I write this, I haven't tried to look very much.

The first one that I want to mention is ThinkGeek's catalog. (Tip of the cap to Jennifer Ouellette.)

As usual, there are some special papers on the arXiv, including this one and this one.

Here is another joke arXiv paper. (Tip of the cap to Chad Topaz.)

Here is a roundup of Google's jokes, including the ability to play "Where's Waldo?" on Google Maps.

Saturday, March 31, 2018

Research Soundtrack

There are rare times when research feels like "Chariots of Fire", and others (usually) when it's more like "March of the Toreadors".

Friday, March 30, 2018

A Pitch for My New Novel

As determined from my dice (and this handy chart), here is the pitch for my new novel: A dystopian fairy tale about a dissatisfied doctor's vacation to expose her social media addiction.

By the way, my d30 (where I rolled again for any results from 27–30) rolled 20 three times during this process, and its only roll below 18 was a single 14, with all but those two rolls in the 20s (including a few of at least 27). Clearly, this is a damage die.

Also, can we get a chart like this for cover letters and grant proposals, please?

P.S. A social media addiction should be contrasted with an antisocial media addiction.

(Tip of the cap to Jennifer Ouellette.)

Wednesday, March 28, 2018

Cover Letters When Responding Reviewers

This "sample cover letter" is hilarious!

I read this before at some point, and it's still really funny now. (And also way too close to the truth.)

Tuesday, March 27, 2018

"Interval Signatures of Celebrities and Researchers on Twitter"

In case you ever wanted to compare my tweeting behavior to that of Lance Armstrong and other celebrities (and several network and data scientists), here is your chance.

It's always nice to be analyzed (for my tweeting behavior) alongside luminaries like Katy Perry, Shaquille O'Neal, and Steve Martin. Lots of my peeps from network and data science are also put under the data-analytic microscope (or perhaps I should write 'mesoscope') on this page.

The Perils of Generating Functions (and Submitting a Note from a Parent with an Exam)

When I taught Math 1d, my exam instructions included a joke line that went something along the lines of "You may also use a note from your mother, though you won't need one." One student (and fellow Caltech undergrad) actually got her mother to write this note, which is fantastic (despite the threats against both Lloyd House and the Los Angeles Dodgers).

I had this posted on my door at Georgia Tech when I was a postdoc, and I found the note a year ago today when I was going through an old spiral notebook.

Sunday, March 25, 2018

Congratulations to Dr. Se-Wook Oh!

Congratulations to my D.Phil. student, Dr. Se-Wook Oh, who has officially earned his doctorate from the Mathematical Institute at University of Oxford. (Jon Chapman was nominally added as a local co-supervisor after I moved to UCLA.) His thesis, in corrected form, has officially been approved.

The title of Se-Wook's thesis is Complex Contagions with Lazy Adoption. You can read about some of Se-Wook's work in our joint paper, which was published recently in Chaos.

Tuesday, March 20, 2018

In Conclusion, Hilarity Ensues.

"Hilarity ensues." is acceptable for the Conclusions section of a paper, right?

What Happens in Provo Stays in Provo

I am at the airport — with a 165-minute delay (sigh...) in my flight — to visit the mathematics department at BYU. I am being hosted by Emily Evans, who is on their faculty and is also a friend of mine from college.

I will somehow deal with the fact that I am not allowed to have coffee on campus. :)

Sunday, March 18, 2018

Algorithms in the Form of IKEA Instructions

I think my life could not possibly have been complete without seeing algorithms presented in the form of IKEA instructions. I am highly amused. :)

(Tip of the cap to Lior Pachter.)

We Kid the Statisticians Because We Love Them


(Tip of the cap to Kerstin Nordstrom.)

Saturday, March 17, 2018

Some Really Old Boardgames

Take a look at this article about some really old boardgames (and one from 1940), including one from the 17th century, that are in a collection in the Houghton Library.

I like the cover of "The Magic Ring". :)

(Tip of the cap to Gabrielle Birkman.)

Society for Impure Mathematics (SIM)

I am an active member of SIAM, the Society for Industrial and Applied Mathematics.

Here's a Fun (Alternative) Fact: The Society for Industrial and Applied Mathematics used to be known as "Society for Impure Mathematics" (SIM), because those of us who do applied mathematics are less pure than other types of mathematicians, bless their hearts.

But perhaps this great organization really ought to change its name to "Society for Impure Mathematics", to appease the theoretical mathematicians who like to call themselves "pure" mathematicians.

As you may have gathered, I find the phrasing "pure mathematics" to be incredibly demeaning towards applied mathematics and applied mathematicians. (The term "unadulterated mathematics" is even worse, so I suppose that my subject of choice is "adulterated mathematics".) I really dislike being considered impure, by implication of the term in use. "Pure mathematics" should really be called "theoretical mathematics", just like in every other science.

Additionally, here are two of my tweets on this and related subjects.

Update: I corrected the acronym (I had written "SIP"), because apparently I am having a problem with English today.

Update: If we want to preserve the acronym SIAM and don't mind a bit of redundancy, it can stand for "Society for Impure and Adulterated Mathematics". :)

Visual Illusion: Snakes on a Plane

Enough is enough. I've had it with these ****** illusory snakes on this ******-****** plane.

(Tip of the cap to Maggie Koerth-Baker.)

Friday, March 16, 2018

Old Article: "On the Fracture of Pencil Points"

I got my first taste of solid mechanics (and fracture mechanics) as a kid when attempting to use 'Number 2' pencils, on which I gave up rather quickly. Once they break once, they will soon break again. I switched to "mechanical pencils" (I like the .07 size) when I was very young.

Here is an old article on pencil-tip fracture (by Henry Petroski). The picture below, which comes from an even earlier article, sets up the the geometry of a pencil tip.

(I was thinking about this because a 'Number 2' pencil showed up in The Grimm Legacy, which I am currently reading.)

Thursday, March 15, 2018

RIP Philip J. Davis (1923–2018) and Writing Uncountably Many Articles

Philip J. Davis, an applied mathematician and very prolific writer, died on Tuesday.

I have a pet peeve in the above obituary: Don't write sentences like "He wrote countless books, articles, and book reviews imbued with his personal perspective." in the obituary of a mathematician, especially if he is an analyst (with much work in numerical analysis, in this case). Trust me: it's countable (and, actually, it's finite).

For most of us, we'll be more familiar with the many essays and (especially) book reviews that Davis wrote for SIAM News.

(Tip of the cap to the SIAM Twitter account.)

"Title of a Paper"

Update: It turns out that I did this so quickly that I mixed my Oxford and UCLA affiliations. Oops.

Tuesday, March 13, 2018

Best. Erratum. Ever.

Because they have so many coauthors, one letter wrong in a name led to this. :)

(Tip of the cap to Nalini Joshi, whose 'liking' of this tweet led me to find it.)

Saturday, March 10, 2018

Playing Mario Kart on Google Maps to Celebrate Mario Day!

In celebration of Mario Day (Mar 10), Google is letting people play a version of Mario Kart on Google Maps.

I have a key question: Where are the best places to inflict lightning bolts on people?

In conclusion, come get some!

(Tip of the cap to Gabrielle Birkman, who indicates that there are places to get banana peels and turtle shells.)

The Multiplex Social–Slayage Network of Buffy the Vampire Slayer

Here is the multiplex social–slayage network of Buffy the Vampire Slayer.

This figure is definite fodder for talks. Also, if somebody sets up the adjacencies, we should compute some centrality and versatility measures.

Friday, March 09, 2018

Pure Evil Versus Applied Evil

The new SMBC is brilliant! I love the caption: "Most of the time when people call something pure evil, they're actually talking about applied evil." ;)

Feedback on Homework Assignments: Getting the Important Stuff Right

As part of the feedback that I once gave to Teaching Committee (to be passed on to the lecturer) on some of the mathematics material in Oxford, I once wrote: "dynamics: The Roadrunner's name is incorrect on homework sheet 2."

You've got to get the important stuff right.

(My submitted feedback also included more substantial comments.)

I also told the lecturer about this in person, of course. :)


New Word Proposal: "Scientificially"

I asked a student if a paper draft of mine passes muster with her "scientificially".

It was just a typo, but I may have to adopt this as a new word for when somebody does something artificial in science.

Example usage: "Those data were estimated scientificially to follow a power law."

Wednesday, March 07, 2018

Video project: "Faces of Women in Mathematics"

Last month, Irina Linke (Director) and Eugénie Hunsicker (Producer) collected videos of women mathematicians, and today they released their compilation video.

Quoting the project page: "In February 2018, women mathematicians from all over the world responded to a call for clips in which they were asked to introduce themselves. The result includes 146 clips of 243 women mathematicians from 36 different countries and speaking 31 different languages. Supported by the Committee for Women in Mathematics of the International Mathematical Union."

Take a look at the video!

I met Eugénie, a fellow Somervillian, at last summer's Somerville mathematics reunion (and informal Erdmann-fest). I just found out that she is also a fellow Project NExTer (i.e., a fellow 'dot').

Tuesday, March 06, 2018

"Hyperchaos" in the White House

I saw "CHAOS" trending on Twitter this morning, so I automatically looked it up, before seeing that it was about politics and then moving on to something else.

And now I see this article, which predominantly consists of an interview with nonlinear dynamicist (and pioneer of chaos) Jim Yorke, including discussions about both mathematical chaos and hyperchaos.

Here is how the part with Yorke begins: "That's not chaos, according to James A. Yorke, Distinguished University Professor of Mathematics and Physics at the University of Maryland at College Park." It goes on from there.

Just think about it: Jim Yorke, an expert in chaotic dynamics, was interviewed by CNN about Donald Trump, precisely because of the former's expertise in mathematical chaos. Yup, we've gone full Illuminati.

(Tip of the cap to Bruno Eckhardt and fuzzy sweatshirt particle.)

Monday, March 05, 2018

"Making Sense of Complexity": A Very Nice Introductory Comic Strip

Sarah Firth's comic strip, Making Sense of Complexity, provides a very nice introduction to complex systems.

Friday, March 02, 2018

Important Advice from Lego Grad Student to Prospective Graduate Students

Pay attention to this excellent advice from Lego Grad Student.

Reaction: YES! YES! A million times YES! (And, for the top tweet, I would change "seriously consider" to "absolutely go to".)

P.S. Lego Grad Student is awesome.

Playing "Soliton" in "Scrabble" (Lexulous)

Take a look at what I just played in “Scrabble” (Lexulous).

Proposal: Use Computational Topology to Study Aversion to Pictures of Holes

Clearly, we need to use topological data analysis (in which one tries to algorithmically compute things like holes and their generalizations) to study aversions to images of clusters of holes.

For science!

Thursday, March 01, 2018

Is 1 the Loneliest Number?

I like (several renditions of) the song "One (is The Loneliest Number)", but I get irked every time I hear following line "One is a number divided by two", because that is just a trivial existence statement.

(Some — most? — versions of the song actually have the line "One is the number divided by two", which is even worse, because of the "the".)

I suppose that this doesn't bother anybody else?

Is There a Mathematical Formula for How Long it Takes for a Child to Ask "Are We There Yet?"?

Well, I find the formula to be rather dubious, though I am highly amused to see it.

I was looking at Dwight Barkley's Wikipedia page, and I noticed that apparently he is also known for deriving an equation to estimate how long it will be until a child in a car asks the question "are we there yet?"

You can read about it (and see the equation) in this short article.

"Complex Contagions with Timers"

A new paper of mine just came out today. This paper was such a pain to write and the page proofs were also a royal pain, so it's a relief that it's finally out. Here are the details.

Title: Complex Contagions with Timers

Authors: Se-Wook Oh and Mason A. Porter

Abstract: There has been a great deal of effort to try to model social influence—including the spread of behavior, norms, and ideas—on networks. Most models of social influence tend to assume that individuals react to changes in the states of their neighbors without any time delay, but this is often not true in social contexts, where (for various reasons) different agents can have different response times. To examine such situations, we introduce the idea of a timer into threshold models of social influence. The presence of timers on nodes delays adoptions—i.e., changes of state—by the agents, which in turn delays the adoptions of their neighbors. With a homogeneously-distributed timer, in which all nodes have the same amount of delay, the adoption order of nodes remains the same. However, heterogeneously-distributed timers can change the adoption order of nodes and hence the “adoption paths” through which state changes spread in a network. Using a threshold model of social contagions, we illustrate that heterogeneous timers can either accelerate or decelerate the spread of adoptions compared to an analogous situation with homogeneous timers, and we investigate the relationship of such acceleration or deceleration with respect to the timer distribution and network structure. We derive an analytical approximation for the temporal evolution of the fraction of adopters by modifying a pair approximation for the Watts threshold model, and we find good agreement with numerical simulations. We also examine our new timer model on networks constructed from empirical data.

Tuesday, February 27, 2018

Children to be Named Later (Best. Erratum. Ever.)

The excellent new book by Kiss, Miller, and Simon on epidemics and networks also has an erratum that is one of my all-time favorites. (See their website of errata.)

In fact, I think this error is a feature of the book, rather than a bug (especially given that I automatically think of Paul Erdős). By the way, the book itself is awesome, so go take a look at it. Here is a screenshot of the erratum.

(Tip of the cap to my Ph.D. student Yacoub Kureh for pointing this out to me in our meeting today. This erratum is an instant classic.)

Some Very Cool Outdated Words

This is brilliant. (I have heard of some of these before.) We need to bring back some of these words.

Sunday, February 25, 2018

Gummy Bear Genetics

Stripe orientation appears to be independent of genetic inheritance in Gummy Bears.

Thursday, February 22, 2018

Alan Kay's 1972 Vision of the Personal Computer

This is very, very cool!

"Opinion Formation and Distribution in a Bounded-Confidence Model on Various Networks"

Another of my papers came out in final form today. This work was led by my former (and excellent) undergraduate student Flora Meng. Here are the details.

Title: Opinion Formation and Distribution in a Bounded-Confidence Model on Various Networks

Authors: X. Flora Meng, Robert A. Van Gorder, and Mason A. Porter

Abstract: In the social, behavioral, and economic sciences, it is important to predict which individual opinions eventually dominate in a large population, whether there will be a consensus, and how long it takes for a consensus to form. Such ideas have been studied heavily both in physics and in other disciplines, and the answers depend strongly both on how one models opinions and on the network structure on which opinions evolve. One model that was created to study consensus formation quantitatively is the Deffuant model, in which the opinion distribution of a population evolves via sequential random pairwise encounters. To consider heterogeneity of interactions in a population along with social influence, we study the Deffuant model on various network structures (deterministic synthetic networks, random synthetic networks, and social networks constructed from Facebook data). We numerically simulate the Deffuant model and conduct regression analyses to investigate the dependence of the time to reach steady states on various model parameters, including a confidence bound for opinion updates, the number of participating entities, and their willingness to compromise. We find that network structure and parameter values both have important effects on the convergence time and the number of steady-state opinion groups. For some network architectures, we observe that the relationship between the convergence time and model parameters undergoes a transition at a critical value of the confidence bound. For some networks, the steady-state opinion distribution also changes from consensus to multiple opinion groups at this critical value.

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.)