Tuesday, May 22, 2018
Thursday, May 17, 2018
(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"
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.
Mathematics and physics get the familiar, cheesy writing-in-the-mirror treatment in some of these.
(Tip of the cap to Justin Howell.)
My first publication (except items in @Caltech's newspaper) was not mathematical or scientific in any way. It was a Dungeons & Dragons character!— Mason Porter (@masonporter) May 15, 2018
I won a contest to design the thief on a cover of Polyhedron.
(For it, I corresponded with editor @erikmona.) #myfirstpublication pic.twitter.com/tTfFHVFdPk
Saturday, May 12, 2018
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
(Tip of the cap to Jane Shevtsov.)
Wednesday, May 09, 2018
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.
Here is the video of my tutorial on paper-writing in applied mathematics: https://t.co/uAbUatOpnS— Mason Porter (@masonporter) May 9, 2018
For reasons unbenownst to me, YouTube decided to classify it as a "comedy".
Maybe that's a feature, rather than a bug?
You can also download the slides.
I hope that people find it helpful!
Tuesday, May 08, 2018
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
Thursday, May 03, 2018
Tuesday, May 01, 2018
Sunday, April 29, 2018
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
Hurray! Science vindicates my longstanding practice, learned at age 12, of using TWO SPACES after periods in text. NOT ONE SPACE. Text is easier to read that way. Of course, on twitter, I use one space, given 280 characters. https://t.co/4xI6sVbF88 Will arm-wrestle @Neuro_Skeptic pic.twitter.com/XpEr4KFR4x— Nicholas A. Christakis (@NAChristakis) April 28, 2018
Wednesday, April 25, 2018
Tuesday, April 24, 2018
Monday, April 23, 2018
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
Tuesday, April 17, 2018
They’re not bad. I wouldn’t call them gorgeous, though.
Sunday, April 15, 2018
Look at the back of this bag, look carefully at the bottom left corner … 🤩 pic.twitter.com/P5SusNDYtY— Nalini Joshi (@monsoon0) April 16, 2018
Monday, April 09, 2018
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
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
While navigating the menus, I managed to get eaten by a grue.
There are errors in some of the D & D categorizations.
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
Friday, March 30, 2018
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
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
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.
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.
As a @Caltech undergraduate, I taught a probability course (Math 1d) and introduced freshmen to the glories of generating functions.— Mason Porter (@masonporter) March 27, 2018
My exam instructions included a line like: "You may also use a note from your mother, though you won't need one."
One student took me up on it. pic.twitter.com/I2Ocif9ttA
Sunday, March 25, 2018
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
I will somehow deal with the fact that I am not allowed to have coffee on campus. :)
Sunday, March 18, 2018
(Tip of the cap to Lior Pachter.)
(Tip of the cap to Kerstin Nordstrom.)
Saturday, March 17, 2018
I like the cover of "The Magic Ring". :)
(Tip of the cap to Gabrielle Birkman.)
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.
From now on, can we say "theoretical mathematics" instead of "pure mathematics"? It's much less obnoxious.— Mason Porter (@masonporter) August 25, 2017
From me, an impure mathematician
The Mathematics Subject Classification (MSC), required on the AMS cover sheet when applying for US mathematics faculty jobs, is very poorly suited for classifying applied mathematicians and leads to interdisciplinary applicants falling through the cracks.https://t.co/zcJ0vmArv4 pic.twitter.com/6KC4pg2f1y— Mason Porter (@masonporter) December 2, 2017
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". :)
Snakes appear to move. pic.twitter.com/HggajNQsHY— Akiyoshi Kitaoka (@AkiyoshiKitaoka) March 17, 2018
(Tip of the cap to Maggie Koerth-Baker.)
Friday, March 16, 2018
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
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.)
I’ll soon be giving what amounts to a tutorial for my UCLA Ph.D. students, who will be embarking on writing papers, and — as I was thinking about what materials to prepare — my mind went to a dark, sarcastic place.— Mason Porter (@masonporter) March 15, 2018
(Inspiration from "Title of the Song" by Da Vinci's Notebook.) pic.twitter.com/N1n3xSY6xr
Update: It turns out that I did this so quickly that I mixed my Oxford and UCLA affiliations. Oops.
Tuesday, March 13, 2018
This is quite a correction for the misspelling of one author's name by a single letter. pic.twitter.com/PJgwmETSIj— Retraction Watch (@RetractionWatch) March 13, 2018
(Tip of the cap to Nalini Joshi, whose 'liking' of this tweet led me to find it.)
Saturday, March 10, 2018
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 Buffy social network: slayage and love links. https://t.co/xwQ0DoKpAG— Peter Sheridan Dodds (@peterdodds) March 11, 2018
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
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. :)
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
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
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
Friday, March 02, 2018
It's tempting to fixate on specific professors or features of departments, and to get sold by their pitches. And that all matters. But you never know how your research interests will change over time. What remains constant and critical is the need for caring and supportive peers.— Lego Grad Student (@legogradstudent) March 2, 2018
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.
Thursday, March 01, 2018
(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?
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.
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
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.)
20 Very Obscure, Very Specific Ancient Jobs eg "Nob Thatcher - Also spelled knob thatcher, this delightful occupation may sound like a Medieval insult, but was the term for a wig-maker." https://t.co/iBrkPdUWWK— Jennifer Ouellette (@JenLucPiquant) February 27, 2018
Sunday, February 25, 2018
Gummy Bear genetics pic.twitter.com/XEkHuoSAz2— Scott Kerr (@scott_kerr) February 25, 2018
Thursday, February 22, 2018
Alan Kay's 1972 vision of the personal computer: "Let's just do it!" Fundamental design principles of computation, robustness & evolvability, anticipates issues in augmented intelligence & AI-human cooperation (user just a process, too) ht @michael_nielsen https://t.co/8Wn3pXQNkl pic.twitter.com/BC1oW9883N— Jessica Flack (@C4COMPUTATION) February 21, 2018
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
My mathematical haiku are part of a collection of haiku published in Journal of Humanistic Mathematics in January 2018: https://t.co/ZbG0JEBgL6— Mason Porter (@masonporter) February 22, 2018
(Yes, even my haiku sometimes include sarcasm.) pic.twitter.com/ogPXYmmR9W
(Thanks to Paul Glendinning for the Twitter 'mention', from which I learned that my haiku made it into the article.)
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
Alarming Comics #1 (1957) pic.twitter.com/tn7wzIxKlC— Panel Pulp (@panelpulp) February 19, 2018
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
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"
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
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.)
There's a new edition of "Surely You're Joking, Mr. Feynman" that just came out this month. Funnily and interestingly, the photo on the cover is the same as before, but the pocket protector is gone. How unfashionable! @dschwa8059 @phalpern https://t.co/wLaCGynpS2 via @amazon pic.twitter.com/7MOrBVnzVa— Ash Jogalekar (@curiouswavefn) February 14, 2018
(Tip of the cap to John Dudley.)
Tuesday, February 13, 2018
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
And this is why we still need editors in the age of text-scanning software. pic.twitter.com/EiDeW4FiGZ— Markus Eichhorn (@markus_eichhorn) February 8, 2018
(Tip of the cap to Jennifer Ouelette.)
Sunday, February 04, 2018
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
Thursday, February 01, 2018
In addition to these three categories, no face is detected in 24 images.
A Dozen Ways To Divide The United Kingdom pic.twitter.com/LuMZ8hC3tG— Terrible Maps (@TerribleMaps) February 1, 2018
(Tip of the cap to Melina Freitag.)
Tuesday, January 30, 2018
Monday, January 29, 2018
Word(s) of the day: “compass grass”, “clock grass” - common names for kinds of beach grass (Ammophila), given for their habit of inscribing perfect circles in sand when their leaves are swung by the wind.— Robert Macfarlane (@RobGMacfarlane) January 29, 2018
Photo by @JamesPMarsden (”8.30 on the sand-clock”) pic.twitter.com/NvBN2O4V9e
Wednesday, January 24, 2018
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
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
Though it's still Billy Joel to me!
(Tip of the cap to Todd Wilkinson.)
Friday, January 19, 2018
(Tip of the cap to David Kung.)
Monday, January 15, 2018
Friday, January 12, 2018
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
Tuesday, January 09, 2018
What Happens at the Joint Mathematics Meetings Stays at the Joint Mathematics Meetings (2018 Edition)
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.
I made it to the 2018 Joint Math Meetings (@JointMath)! #JMM2018— Mason Porter (@masonporter) January 10, 2018
I'll try not to get booed during my talk this year, like I was in 2005. (With people from an impending on-campus faculty interview in the audience.)
You know you've made it when you're booed at a math conference.
Saturday, January 06, 2018
Friday, January 05, 2018
Thursday, January 04, 2018
Wednesday, January 03, 2018
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
(Tip of the cap to Sydney Padua.)