Thursday, December 21, 2023

Dodgers Sign Pitcher Yoshinobu Yamamoto!

The Dodgers have signed star pitcher Yoshinobu Yamamoto, who is joining the Majors from Japan. Now we have our ace starting pitcher!

This follows on our recent trade for pitcher Tyler Glasnow and our signing of free agent Shohei Ohtani.

What the Dodgers do is Moneyball with money.

Monday, December 18, 2023

"Human-Network Regions as Effective Geographic Units for Disease Mitigation"

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

Title: "Human-Network Regions as Effective Geographic Units for Disease Mitigation"

Authors: Clio Andris, Caglar Koylu, and Mason A. Porter

Abstract: Susceptibility to infectious diseases such as COVID-19 depends on how those diseases spread. Many studies have examined the decrease in COVID-19 spread due to reduction in travel. However, less is known about how much functional geographic regions, which capture natural movements and social interactions, limit the spread of COVID-19. To determine boundaries between functional regions, we apply community-detection algorithms to large networks of mobility and social-media connections to construct geographic regions that reflect natural human movement and relationships at the county level in the coterminous United States. We measure COVID-19 case counts, case rates, and case-rate variations across adjacent counties and examine how often COVID-19 crosses the boundaries of these functional regions. We find that regions that we construct using GPS-trace networks and especially commute networks have the lowest COVID-19 case rates along the boundaries, so these regions may reflect natural partitions in COVID-19 transmission. Conversely, regions that we construct from geolocated Facebook friendships and Twitter connections yield less effective partitions. Our analysis reveals that regions that are derived from movement flows are more appropriate geographic units than states for making policy decisions about opening areas for activity, assessing vulnerability of populations, and allocating resources. Our insights are also relevant for policy decisions and public messaging in future emergency situations.

Saturday, December 16, 2023

2023 Hank Aaron Awards

The 2023 Hank Aaron Awards for the best offensive player in each league have been awarded to Shohei Ohtani (formerly of the Angels and now of the Dodgers) and Ronald Acuña, Jr. (of the Braves).

Tuesday, December 12, 2023

"Low-Dimensional Behavior of a Kuramoto Model with Inertia and Hebbian Learning"

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

Title: Low-Dimensional Behavior of a Kuramoto Model with Inertia and Hebbian Learning

Authors: Tachin Ruangkriengsin and Mason A. Porter

Abstract: We study low-dimensional dynamics in a Kuramoto model with inertia and Hebbian learning. In this model, the coupling strength between oscillators depends on the phase differences between the oscillators and changes according to a Hebbian learning rule. We analyze the special case of two coupled oscillators, which yields a five-dimensional dynamical system that decouples into a two-dimensional longitudinal system and a three-dimensional transverse system. We readily write an exact solution of the longitudinal system, and we then focus our attention on the transverse system. We classify the stability of the transverse system’s equilibrium points using linear stability analysis. We show that the transverse system is dissipative and that all of its trajectories are eventually confined to a bounded region. We compute Lyapunov exponents to infer the transverse system’s possible limiting behaviors, and we demarcate the parameter regions of three qualitatively different behaviors. Using insights from our analysis of the low-dimensional dynamics, we examine the original high-dimensional system in a situation in which we draw the intrinsic frequencies of the oscillators from Gaussian distributions with different variances.

Saturday, December 09, 2023

Sunday, December 03, 2023

Jim Leyland Elected to Baseball's Hall of Fame

Former manager Jim Leyland has been elected to Major League Baseball's Hall of Fame in a vote of the Contemporary Baseball Era Non-Players Committee.

"Leyland received 15 of a possible 16 votes (93.8%), while Piniella received 11 (68.8%), White received 10 (62.5%) and Gaston, Johnson, Montague, Peters and West each received fewer than five votes." A candidate needed to receive 12 or more votes (i.e., from at least 75% of the committee) to be elected.

Jay Jaffe wrote a particularly compelling case in favor of Bill White.

Wednesday, November 29, 2023

2023 Relievers of the Year

Félix Bautista of the Baltimore Orioles and Devin Williams of the Milwaukee Brewers are this year's Relievers of the Year in Baseball.

Tuesday, November 28, 2023

2023 Comeback Players of the Year

Reliever Liam Hendricks of the Chicago White Sox and outfielder (and also infielder, when he was with the Dodgers) Cody Bellinger of the Chicago Cubs have been named Baseball's 2023 Comeback Players of the Year.

"A Density Description of a Bounded-Confidence Model of Opinion Dynamics on Hypergraphs"

Another of my papers has now been published in final form. Here are some details.

Title: A Density Description of a Bounded-Confidence Model of Opinion Dynamics on Hypergraphs

Authors: Weiqi Chu and Mason A. Porter

Abstract: Social interactions often occur between three or more agents simultaneously. Examining opinion dynamics on hypergraphs allows one to study the effect of such polyadic interactions on the opinions of agents. In this paper, we consider a bounded-confidence model (BCM), in which opinions take continuous values and interacting agents compromise their opinions if they are close enough to each other. We study a density description of a Deffuant–Weisbuch BCM on hypergraphs. We derive a rate equation for the mean-field opinion density as the number of agents becomes infinite, and we prove that this rate equation yields a probability density that converges to noninteracting opinion clusters. Using numerical simulations, we examine bifurcations of the density-based BCM's steady-state opinion clusters and demonstrate that the agent-based BCM converges to the density description of the BCM as the number of agents becomes infinite.

Friday, November 24, 2023

"Supracentrality Analysis of Temporal Networks with Directed Interlayer Coupling" (Second Edition)

The unnecessary second edition of the book Temporal Network Theory is now out. It includes a second edition of a chapter that I coauthored. Here are a few details.

Title: Supracentrality Analysis of Temporal Networks with Directed Interlayer Coupling

Authors: Dane Taylor, Mason A. Porter, and Peter J. Mucha

Abstract: We describe centralities in temporal networks using a supracentrality framework to study centrality trajectories, which characterize how the importances of nodes change with time. We study supracentrality generalizations of eigenvector-based centralities, a family of centrality measures for time-independent networks that includes PageRank, hub and authority scores, and eigenvector centrality. We start with a sequence of adjacency matrices, each of which represents a time layer of a network at a different point or interval of time. Coupling centrality matrices across time layers with weighted interlayer edges yields a supracentrality matrix C(ω), where ω controls the extent to which centrality trajectories change with time. We can flexibly tune the weight and topology of the interlayer coupling to cater to different scientific applications. The entries of the dominant eigenvector of C(ω) represent joint centralities, which simultaneously quantify the importances of every node in every time layer. Inspired by probability theory, we also compute marginal and conditional centralities. We illustrate how to adjust the coupling between time layers to tune the extent to which nodes’ centrality trajectories are influenced by the oldest and newest time layers. We support our findings by analysis in the limits of small and large ω.

Thursday, November 16, 2023

2023 Most Valuable Player Awards

Major League Baseball has announced its 2023 Most Valuable Players. To nobody's surprise, Shohei Ohtani of the Los Angeles Angels was the unanimous MVP in the Americal League. Also to nobody's surprise, Ronald Acuña, Jr. of the Atlanta Braves won the MVP award handily in the National League. Acuña, Jr. also won the MVP unanimously (which I hadn't expected), and this marks the first time that both MVPs were unanimous. Ohtani is the first baseball player ever to twice be name a unanimous MVP.

The National League MVP voting was interesting. Mookie Betts of the Los Angeles Dodgers got all 30 second-place votes, and Freddie Freeman (Dodgers) and Matt Olson (Braves) split all of the third-place and fourth-place voters (with Freeman getting 17 of the former and 13 of the latter to obtain 4 more points than Olson). Rookie of the Year Corbin Carroll of the Arizona Diamondbacks finished fifth in the voting and garnered 20 of the 30 fifth-place votes.

Wednesday, November 15, 2023

2023 Cy Young Awards

As with Major League Baseball's awards earlier this week, the 2023 Cy Young Awards were awarded to the expected pitchers. Blake Snell of the San Diego Padres won handily in the National League, and Gerrit Cole of the New York Yankees won unanimously in the American League.

Tuesday, November 14, 2023

2023 Managers of the Year

The Managers of the Year have been announced. Skip Schumaker of the Miami Marlins won in the National League and Brandon Hyde of the Baltimore Orioles won in the American League.

Monday, November 13, 2023

2023 Rookies of the Year

Baseball's 2023 Rookies of the Year are Gunnar Henderson of the Baltimore Orioles and Corbin Carroll of the Arizona Diamondbacks.

Both selections were unanimous, and it was clear that both selections would either be unanimous or very nearly so (and it was clear that Carroll would win unanimously).

Saturday, November 11, 2023

What Happens in San Juan Capistrano Stays in San Juan Capistrano (2023 Edition)

I was just in San Capistrano for a bit more than a day to hang out with friends.

Thursday, November 09, 2023

2023 Silver Slugger Awards

The 2023 Silver Slugger awards were announced today. This includes inaugural team awards for the Braves in the National League and the Rangers in the American League.

Sunday, November 05, 2023

Wednesday, November 01, 2023

What Happens in Pittsburgh Stays in Pittsburgh

I am off to Pittsburgh for a few days!

Thursday, October 26, 2023

RIP Gary Lorden (1941–2023)

Gary Lorden, a profesor emeritus of mathematics at Caltech, died last night. In addition to being a mathematics professor, Gary held many leadership positions at Caltech. He was the only statistician in Caltech's math department, and I TAed for him during my junior year in the inaugural edition of the so-called "new core", which included major changes in Math 1 and Math 2. I got my gig as a consultant for the movie "Meet Dave" through Gary. He was also a very kind person.

Update (10/30/23): Caltech has posted a short obituary.