Friday, December 14, 2018
(Tasty, tasty reproducibility.)
(Tip of the cap to Javier Buldú.)
Update: Now that I think of it, "Sweet, sweet reproducibility." would have been better phrasing, given its larger set of allusions.
Wednesday, December 12, 2018
Title: "Variability in Fermi–Pasta–Ulam–Tsingou Arrays Can Prevent Recurrences"
Authors: Heather Nelson, Mason A. Porter, and Bhaskar Choubey
Abstract: In 1955, Fermi, Pasta, Ulam, and Tsingou reported recurrence over time of energy between modes in a one-dimensional array of nonlinear oscillators. Subsequently, there have been myriad numerical experiments using homogenous FPUT arrays in the form of chains of ideal, nonlinearly coupled oscillators. However, inherent variations (e.g., due to manufacturing tolerance) introduce heterogeneity into the parameters of any physical system. We demonstrate that such tolerances degrade the observance of recurrences, often leading to complete loss in moderately-sized arrays. We numerically simulate heterogeneous FPUT systems to investigate the effects of tolerances on dynamics. Our results illustrate that tolerances in real nonlinear oscillator arrays may limit the applicability of results from numerical experiments on them to physical systems, unless appropriate heterogeneities are taken into account.
Sunday, December 09, 2018
These are not good picks, especially the one of Harold Baines. They belong more in the Hall of Very Good, rather than in the Hall of Fame. They had very good careers and compiled large numbers in various stats, but in my opinion they don't belong in the Hall of Fame. One of the things to think about when considering whether a player raises or lowers the standards of the Hall at their position. In my view, Lee Smith is a borderline case and I would put him just below the border, but he was the all-time saves leader for a while (and, in general, I can see the arguments in his favor), and he got many Hall of Fame votes for years. Thus, I only view this as a mildly bad pick. I understand it, but I wouldn't put him in the Hall. Part of the issue with Lee Smith has always been the overrating of saves, and I am not surprised that he got in through the Today's Game Era Committee, given the many votes he got from writers over the years in the regular voting. So I can mostly understand his case. But Harold Baines? He was a very good player, but he really lowers the bar at his position. He never got a sniff from the writers, nor did he deserve it.
I'm looking forward to the regular ballot, which will get us Mariano Rivera (who may break the record for highest voting percentage), Edgar Martínez (finally!), Roy Halladay, and maybe (and hopefully!) Mike Mussina will make it. Those four all richly deserve enshrinement in the Hall of Fame.
Maybe Lee Smith's election will help Billy Wagner's case?
Friday, December 07, 2018
Comment 2: Apparently, some of my what we did in mathematics in Somerville was an even better idea than I thought. ;)
'The provision of chocolate cookies had a significant effect on course evaluation. These findings question the validity of (student evaluations of teaching) and their use in making widespread decisions within a faculty.' HT @KStackWhitney (photo: Dschwen) https://t.co/lO1v18tmf5 pic.twitter.com/N6epK3GinU— Erika Marín-Spiotta (@emsaurios) December 7, 2018
(Tip of the cap to Jacquelyn Gill.)
Tuesday, December 04, 2018
Wolfram Alpha thinks that I may want to find jewelry, even though I asked it about a differential equation. pic.twitter.com/PpfoFUbEUb— Mason Porter (@masonporter) December 4, 2018
Wow! I wonder what happens when laundered anti-money collides with laundered money?
Tuesday, November 27, 2018
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
Monday, November 26, 2018
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.