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...
My name is Mason Porter. I am a Professor in the Department of Mathematics at UCLA. Previously I was Professor of Nonlinear and Complex Systems in the Mathematical Institute at University of Oxford. I was also a Tutorial Fellow of Somerville College.
Tuesday, November 27, 2018
Extra Special Mathematics Terminology
One of my favorite terminology fails in mathematics is the notion of an "extra special group" (which has the added bonus that my undergraduate abstract-algebra professor was unable to say it without also giggling): https://t.co/BsW1dgDYaC
— Mason Porter (@masonporter) November 27, 2018
So inspired!#terminologyfail
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.
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. ;)
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.
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
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!
#Twisty #puzzle guest tweet. #Hyperbolic #Rubik's cube analogue shown solving in the Poincaré disk model. 24-color puzzle based on the regular {7,3} #tiling. https://t.co/fH15fczvKw pic.twitter.com/3mHMGiygQ2
— Tiling Bot (@TilingBot) November 18, 2018
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.
The Mathematics Subject Classification does an "awesome" job of classifying me: https://t.co/chQW9cCotC
— Mason Porter (@masonporter) November 16, 2018
This classification ontology is horrible for applied mathematicians in general, and that can really hurt them on the job market. pic.twitter.com/DnYYBI2Muh
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.
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.
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.
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!
The 2018 class of Major League Baseball rookies was very strong indeed!
Sunday, November 11, 2018
"Roll for Initiative"
I think I've decided on what message to put on my tombstone. ;) 👻 pic.twitter.com/i7CbQp9xJO
— Mason Porter (@masonporter) November 11, 2018
(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.
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
Wow!
Lithops, South African plants that have evolved to look like stones. pic.twitter.com/6NQqniKZbJ
— Back To Nature (@backt0nature) November 5, 2018
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. ;)
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.
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.