Isostaticity of Constraints in Jammed Systems of Soft Frictionless Platonic Solids

The average number of constraints per particle $$ in mechanically stable systems of Platonic solids (except cubes) approaches the isostatic limit at the jamming point ($\rightarrow 12$), though average number of contacts are hypostatic. By introducing angular alignment metrics to classify the degree of constraint imposed by each contact, constraints are shown to arise as a direct result of local orientational order reflected in edge-face and face-face alignment angle distributions. With approximately one face-face contact per particle at jamming chain-like face-face clusters with finite extent form in these systems.Comment: 4 pages, 3 figures, 4 tabl

The Evolution of Bias - Generalized

Fry (1996) showed that galaxy bias has the tendency to evolve towards unity, i.e. in the long run, the galaxy distribution tends to trace that of matter. Generalizing slightly Fry's reasoning, we show that his conclusion remains valid in theories of modified gravity (or equivalently, complex clustered dark energy). This is not surprising: as long as both galaxies and matter are subject to the same force, dynamics would drive them towards tracing each other. This holds, for instance, in theories where both galaxies and matter move on geodesics. This relaxation of bias towards unity is tempered by cosmic acceleration, however: the bias tends towards unity but does not quite make it, unless the formation bias were close to unity. Our argument is extended in a straightforward manner to the case of a stochastic or nonlinear bias. An important corollary is that dynamical evolution could imprint a scale dependence on the large scale galaxy bias. This is especially pronounced if non-standard gravity introduces new scales to the problem: the bias at different scales relaxes at different rates, the larger scales generally more slowly and retaining a longer memory of the initial bias. A consistency test of the current (general relativity + uniform dark energy) paradigm is therefore to look for departure from a scale independent bias on large scales. A simple way is to measure the relative bias of different populations of galaxies which are at different stages of bias relaxation. Lastly, we comment on the possibility of directly testing the Poisson equation on cosmological scales, as opposed to indirectly through the growth factor.Comment: 8 pages, 2 figures. References added. Accepted for publication in Physical Review

Gallium(III)-Promoted Halocyclizations of 1,6-Diynes

Adrian Landreth was an REU student, summer 2014Cyclization of 1,6-diynes promoted by stoichiometric Ga(III) halides produces vinyl halides in good to excellent yields. Under acidic conditions, initially formed iodocyclization products undergo in situ Friedel-Crafts cyclizations, giving access to iodo-indenopyridines. The application of the vinyl halides in cross-coupling reactions has been explored, and mechanistic aspects of the cyclization are discussed.HIGMS CMLD Initiative (P50 GM067041) NSF REU - Adrian Landreth support (CHE 1156666) NSF - NMR purchase (CHE 0619339) NSF - HRMS purchase (CHE0443618

Information-Based Particle Flow with Convergence Control

A new formulation of the Gaussian particle flow filter is presented using an information theoretic approach. The developed information-based form advances the Gaussian particle flow framework in two ways: it imparts physical meaning to the flow dynamics and provides the ability to easily include modifications for a non-Bayesian update. An orbit determination simulation with high initial uncertainty is used to demonstrate the consistent, robust performance of the information flow filter in situations where the extended Kalman filter fails

The Vice Presidential Home State Advantage Reconsidered: Analyzing the Interactive Effect of Home State Population and Political Experience, 1884-2008

Previous research has found that presidential tickets perform particularly well in a vice presidential candidate\u27s home state when that state is relatively low in population. In this article, we argue that selecting a vice presidential candidate from a small state is not sufficient to produce a large vice presidential home state advantage; rather, state population should matter only insofar as the vice presidential candidate has extensive experience within that state\u27s political system. Analysis of presidential election returns from 1884 through 2008 demonstrates the statistically significant interactive effect of home state population and political experience on the size of the vice presidential home state advantage. The models presented in the article perform much better than models that do not account for this interactive effect

Will the Vice Presidential Candidates Matter this Year? Maybe, But Not the Way You Think

Veepstakes speculation is rampant as we approach the national conventions for both major political parties. Media reports have detailed the wide array of options available to Donald Trump and Hillary Clinton as they decide who will be their number twos for this campaign, and perhaps for four or eight years to come. Who will Trump and Clinton pick? That depends on each candidate’s goals – both for the remainder of the presidential campaign and after Nov. 8. Political observers widely agree that the most important characteristic to look for in a running mate is the ability to serve as president in the event of unforeseen circumstances, like a president’s death, incapacitation, resignation or impeachment. However, when campaign staff and trusted political advisers vet potential running mates, they are certain to also weigh political considerations. That is, whether a given running mate will help or hurt the presidential ticket, with voters in general or with a key voting group. Particularly if the campaign is at a competitive disadvantage, its strategists may look to the running mate as a potential “game changer.” The electoral advantage most commonly associated with vice presidential candidates is geographic. In other words, they are expected to deliver their home state or region in the Electoral College. But do they actually deliver? Usually not. In our book, “The VP Advantage: How Running Mates Influence Home State Voting in Presidential Elections,” we employed a multi-method approach to empirically test the purported home state advantage. We used both state-level election returns since 1884 and individual-level survey data since 1952 in our analysis. Ultimately, we found no evidence of a general vice presidential home state advantage, on average. Based upon the data, it is unlikely that Hillary Clinton’s or Donald Trump’s running mate will deliver a crucial battleground state, like Ohio or Virginia. Instead, the presidential candidates would be wise to select a respected running mate who can effectively serve as vice president

Presidential Versus Vice Presidential Home State Advantage: A Comparative Analysis of Electoral Significance, Causes, and Processes, 1884-2008

This article compares the electoral significance, causes, and processes associated with presidential versus vice presidential home state advantages. Our analysis of presidential election returns from 1884 through 2008 demonstrates that presidential candidates generally receive a large, statistically significant home state advantage. However, vice presidential home state advantages are statistically negligible and conditioned on the interactive effect of political experience and state population. Furthermore, the results indicate that the mobilization of new voters primarily accounts for presidential home state advantage, while vice presidential home state advantage is mainly due to the conversion of existing voters. Although home state advantages do occur in presidential elections, according to our analysis, a presidential or vice presidential home state advantage has not changed the outcome of any presidential election since 1884